I tried lifting my mood by going out but the problem is that I've always feel like my actions are being watched all the time.
You need to talk to your Dad about this, and now. Is your Mom still in the picture? Do you have friends or other relatives you can talk to? What you need is to get into therapy ASAP. If you get like this when your Dad's away, call him. If you can't get him, call a hotline. I don't know what happened to trigger this, but the sooner you get adult help the sooner you can ease down from it. But very first thing, talk to your Dad.
Sympathy! Did something happen to trigger this - a bad event or change in meds? Maybe it’s just hormones out of whack. If mom, dad, grandparents, older siblings are not available for talk, Google “suicide hot line” for other options.
I get the most that you are truly hurting. That your self image is seriously damaged. Deep feelings of body dysmorphism. If you don't know the term it means a terribly poor physical body self image. I think you should seek professional psychiatric help asap. I get the impression of a young woman , 15 who is really emotionally hurting. I feel I can't diagnose since I'm not a mental health professional. Overall you seem to me extremely poor self esteem and a profound sadness because of it. You didn't mention your mom or your relationship with her emotionally. Can you talk to your dad in the evening and/or the weekend? Please get the help you need either in person, by phone or online therapy.
**** Let me say that if you have thought about suicide and have an actual plan or way you'd do it, it is time for immediate intervention. There are suicide prevention hot lines and websites you can contact. That's a mental health crisis and please PLEASE speak to your dad about that immediately. And if you ever feel semi serious about doing this, call 911 or ask your dad to drive you to the ER. I've taken my son. It starts the ball rolling or true help to get you back on track. Depression whether it is just depression or depression and an eating disorder is dangerous to leave untreated sweetie.
With regards to eating as comfort ---I think comforting with food is something a lot of people do (me). We start a reward system of food when growing up. Food is associated with things like celebrations, milestones, happy events. It just gets to be a 'thing' that we find comfort for and let's face it, it tastes good! Managing eating and weight is something many struggle with. However, if you are binging. That is different. That will impact you negatively especially if you get into the cycle of either purging or starvation after. My son answers questions regarding detection of an eating disorder as part of every screening he's now had for his mental health. Providers KNOW what to look for and they know how to treat this. You sound to have other symptoms of depression and anxiety. It's time to get help.
So, your dad. Can you tell him about this? He needs to know. School counselors may help as well. But you are in a position now to probably need a psychiatric care team that will start with perhaps a social worker to evaluate the suicide thoughts and start making a safety plan with you, a psychotherapist to begin treatment such as cognitive behavior therapy and if they deem necessary, either a psychiatrist or what I've come to realize do a fantastic job with medication these days is a psychiatric nurse practitioner. Now, I am not sure where you live. I am not sure what mental health help you have available to you. Let us know, we'll try to help.