It would really be helpful if you could look up your FT3 and FT4 levels so we can see what they are, with reference ranges. How long ago were the tests done?
How long have you been on the Synthroid? What dosage are you on?
Sometimes, thyroid hormone medication can help shrink a goiter if you give it enough time.
Having your thyroid removed is going to make you permanently hypo, just has having Hashimoto's would do, because the antibodies would, eventually, destroy your thyroid so it would no longer produce any hormones. Sometimes, it's easier to balance the hormones, once the thyroid is destroyed (whether by antibodies or removal) because you don't have the thyroid possibly producing hormones, at the same time you're taking medication...
Nobody can tell you how it will affect your weight - that will depend on getting your levels where you need them, but that will be the case whether you have your thyroid removed or whether the antibodies destroy it...
Again, no one can say for sure about your voice. Some people have voice issues after a thyroidectomy that "can" last up to 2-3 months, it doesn't happen to everyone. It's best to not try to use your voice right away - just let everything heal and it should be okay.
It's possible that your cough is thyroid related...you should go ahead and tell your endo; if it's not thyroid related, she will tell you if you need to see another doctor and if it "is" thyroid related she will help deal with it.
ok an update and more questions. I have been to a new doctor and treating with some natural supplements band back on synthroid. TSH is .4 but other thyroid numbers not great. I would have to look them all up. I have developed a chronic cough. My dr says she thinks thyroid pressing on esophagus and time to consider surgical removal. I have ultrasound next week then endoscopy to decide. If I do that, my questions are:
how will this affect my weight? (chronic problem)
how will it affect my voice? (I talk for a living, all day every day)
how long is the recovery?
will this ultimately help me balance thyroid or make things worse?
Both hypothyroidism and hyperthyroidism are known causes of low stomach acid so yes both conditions may cause acid reflux. Until you get your thyroid sorted out you can try other ways to increase stomach acid such as apple cider vinegar or betaine HCL with pepsin. Also digestive enzymes supplements are helpful as well and can be taken by anyone to help with digestion.