It could be fat and could be bloat; how old are you? If you're obsessive about weight that makes it sound like you're a teenager, but if you've aged out of military benefits, not so much. I'd say that the lack of pooping except twice a month, coupled with not many calories and a stomach that still sticks out, is abnormal enough to go to a doctor about, for sure, since you want to rule out something more serious than fat or bloat.
Lots of things can cause constipation, including laxative abuse.
But only having 2-3 bowel movements a month is definitely worrisome.
Short list of possible causes of constipation: not eating enough foods low in fiber, dehydration (not enough water, or electrolyte imbalance, which might be too much or too little electrolytes, not enough exercise (moving around can get our bowels moving around too), stress, eating too much milk or cheese, resisting the urge to have a BM, a bunch of medications, hormonal disorders (hypothyroidism, diabetes, hypercalcemia, and uremia), irritable bowel disorder, and many other medical conditions that affect the intestines.
I'm not a medical professional, but I can talk from my own experience. I very rarely experience any constipation (ever), but I also run everyday and assume that helps keep things moving. The times I have had "a slowing of bowel movements" (so not every day, but still every other day) are times when I've been experiencing a lot of anxiety. When I have high anxiety, I tend to eat a lot less food. I don't count calories now, but most days, I'm around 2200-2800 (I run a lot, so 2800 is fine some days). When I'm feeling so overwhelmed by anxiety, I eat much less (probably closer to 500-1000 calories a day), and that definitely slows my digestive tract down, because there is not enough food in my system to keep things moving forward, at least not quickly. No one needs to run as much as I do, and I don't run in order to eat more food, I just like running, and I like to fuel my body with healthy foods because in order to keep functioning, it needs energy and nutrients. If some days you are eating a lot less than 1300-1400 calories, there may be just not enough "stuff" in your digestive tract for things to move through.
My main concern for you with not going to a doctor is that if there is something physically wrong with your digestive tract or a hormonal issue, this can't be fixed by just trying to eat different foods or drinking more water. I would strongly suggest you google "clinics for uninsured patients near me" and find out what it would take to see a doctor or nurse, even without insurance, at a cost you could afford. I'm sure there are some on-line or tele-clinics for the uninsured that could help you both with your digestive problem and with mental health.
On to the question of whether it is belly fat or just bloating? I have had thyroid issues for many, many years, and hypothyroidism can cause bloating/water retention and an increase in storage of fat specifically around the mid-section. I'm currently at a healthy weight, but I've noticed I've put some fat on my belly and while the rest of me seems very fit, I carry a little extra weight specifically in my abdomen. I've also just spent 5 months on medication that lowers my estrogen, putting me in a menopause like state, although I haven't hit real menopause yet. Menopause, which is brought on by a drop in estrogen levels, causes many people to store fat in the abdomen instead of hips and thighs like they may have when they were younger and had high levels of estrogen. That combined with skipping menstrual cycles might indicate a hormonal issue (PCOS and thyroid issues immediately spring to mind). I'm not saying that you have either of those, but that might be something to rule out. If you are storing extra abdominal fat, this means you have a higher risk of developing insulin resistance or metabolic syndrome, so if you do have higher levels of abdominal fat compared to other parts of your body, that is something that should be a concern. (Not a reason to starve yourself though.)
And, it may be what you think is "4 months pregnant" is actually "normal woman shape" and not an abdominal fat concern at all. We are bombarded with images of women with 6-pack stomachs that our brains start to think that that is "normal" and "healthy" and that a slightly pudgy woman belly is "abnormal", when in fact, that is just a healthy belly, and to get to the "6-pack abs" on a woman, it usually involves dropping to low levels of body fat, which can disrupt or completely stop the menstrual cycle, and is not at all healthy for a woman to have that low body fat for an extended period of time (dangers include bone loss as well as the reduced fertility).
My best guess for you is if the "belly fat" goes away after you have a bowel movement (from anxiety/menstruation) or after your hormones drop (day 2-3ish of the start of a new menstrual cycle), it is probably not fat and just intestinal bulk or bloating. If it stays after you clear out your system, then it might be fat. If you are storing fat specifically in the belly area, I would strongly recommend getting your thyroid/other hormones checked out. If you are not having regular periods, it would be a good idea to visit a gynecologist and make sure everything is ok. People lose their periods for a variety of reasons.
You deserve to have a healthy body and proper medical care. To get to that point, you may need to contact a doctor and work on both your eating disorder and also figure out if there are any underlying medical conditions causing constipation problems.
As Sarah noted, there are a lot of things that can cause the belly bulge, ranging from hormone imbalances to constipation.
Even not eating enough can cause it. The bloating and burping make me wonder if you could have H Pylori - that's a bacteria of the stomach that many of us have, but it doesn't cause trouble until it becomes a dominant bacteria. I've had H Pylori twice and it causes a variety of symptoms, including constipation.
As one who has had constipation issues for a good part of my life, I've learned that it's necessary to consistently make sure you eat adequate fiber, best in the form of vegetables, but whole grains also contain a lot of fiber. When increasing fiber, we have to make sure we drink plenty of water because otherwise the fiber becomes "dry" and won't push on through. It's also possible that, due to your constant constipation, the muscles of your intestines are malfunctioning so they can't contract and push the food through.
You really do need to see a doctor to help you figure out the physical issue, but from dealing with a daughter with an eating disorder, I can tell you it's equally important to find someone to help with the mental health aspect so you can achieve/maintain a healthy body image. You'll learn that our bodies change all the time, so a little tummy pudge isn't anything to worry about. It's also normal to gain a bit tummy pudge as we get older. A mental health professional can help you put everything in perspective.
I'd like to know what you mean by aging out of military benefits. Since you mention Medicaid, are you currently unemployed? Did you recently leave the military and are temporarily in between jobs? I ask because I'm wondering if you were eligible for Tricare, and if so, why did you decide not to hold onto it, which I believe you can do. Can you not afford the premiums? This is some of the best health insurance you can have, and letting it go if you're eligible for it isn't a great decision, so again, I'm wondering what aging out of military benefits means? My understanding, and I could be wrong as things could have changed, is once you have gov't insurance of any kind, including military, you can keep it forever as long as you pay your bills. And again, you can't really get better insurance than gov't insurance. If there's any way to keep it, do so. That might mean talking to an insurance advisor in the gov't to see what your options are and if there's help when you can't afford premiums. So there's that issue. Second, I think your biggest problem is emotional, because it's what probably got you into this place to begin with absent some health problem such as is well discussed above. Your abuse of laxatives probably caused the constipation and also makes it harder to get rid of it. Medication is one of the biggest causes of constipation -- a lot of meds cause it and abuse of a lot of meds, including laxatives, can cause it as well. Usually, it goes away when you stop the med or abuse of the med, but sometimes the body gets stubborn on us if we're unlucky and then we have created a long-term problem, which can be very hard and time consuming to fix and requires a big change in lifestyle, diet, and mental state. Again, absent a physiological problem. You don't say what you eat and you also don't mention exercise. If you were in the military, I assume you exercised regularly. If you got your military benefits as a spouse or some other way, then maybe not. But exercise does keep things moving. If you're sedentary, things get static, and if you've already caused your body to wonder what's going on with the abuse of your evacuation system being static will just make it even harder for your body to remember how it did things when things were working. This doesn't happen to everyone, but it does happen, and it does no good for a person who gets a problem to know that most people don't get that problem. Digestion problems are not an area docs are great at diagnosing or fixing unless it's something that really stands out. Since you don't appear to feel able to see a doctor or therapist right now -- and you know, seeing a therapist is really expensive because you have to see them every week but it's not that expensive to see a doctor once. But once they start ordering tests, the cost is beyond almost everyone if you don't have insurance. That's why I would try to look at the parts of your life you can control on your own in the meantime, which is your diet, how much you exercise, and learning relaxation techniques to relieve stress and anxiety as much as you can while you figure out how to get treatment from a professional. For example, if you eat a lot of red meat, stop. It's really hard for the body to digest. Legumes, nuts and seeds and fish can provide your protein needs and plant protein foods also contain fiber and is just easier for the body to break down without needing a lot of acidity to do so. Now, legumes can also bring bloating and such, but there are so many of them there's usually some that don't bother us and ways to prepare them that makes them less likely to be a problem, and even though they might produce some of the well-known problems, they are good for going to the bathroom. This is just one example of changes you can try among many that might just retrain your body how to go regularly if the problem was caused by that and not by some major physiological problem. Also, imbalances in sexual hormones can cause problems as well, and you seem to be having those. There are plant foods that also might help with that, and so can exercise if you don't exercise and relieving stress. As for those folks with flat stomachs, most of them are very young, which doesn't seem to describe you, and a whole lot of them are taking steroids. They won't tell you that, but take women sprinters -- a few years ago, they suddenly started looking like they had no bellies and had wonderful six packs and it turned out almost all of them were taking steroids. It wasn't natural. The women above are right, a natural belly isn't flat, because the best diet is mostly plant based and that will make it very hard to have a flat stomach. We all want one, men and women, but almost none of us over the age of thirty have one even if we're not at all overweight. This is new, by the way -- people didn't used to really care about this. Anyway, I mainly wanted to add to already great advice above that it is very possible you did this to yourself and therefore can undo it to yourself, and to emphasize that if you can hold onto that gov't insurance, do so. Peace.
I have also that problem love to know the right answer