Thank You for sharing that good luck hope you feel better!
Well, I'm not sure where to start, so I'll begin with a simple welcome to our community.
You said your thyroid levels are normal -- I'm sorry, but I have to disagree. Labs use different reference ranges and many of them use old ranges. AACE changed the range for TSH about 6 yrs ago. The range is now 0.3-3.0, so at 3.95, I'd say you are still hypo and that 25 mcg synthroid is not enough. I'd like to know what your Free T3 and Free T4 levels are. Since this is the weight loss community, it would be good if you could send me a PM with those levels and their reference ranges as listed on the lab report, if you have a copy. If you don't have a copy, I strongly suggest that you get one each time you have labs done and keep it for your records. Most of your symptoms are symptoms of hypothyroidism and although I'm not a doctor, I suspect you are being under treated.
I have hypothyroidism and have been on med for almost 2 years. I've just recently gotten to the point where my levels are right for ME and I can now lose weight.
Your high insulin levels may be due to insulin resistance. What does your doctor say about that? I just did a quick search and read that high insulin levels can cause acanthosis nigricans. It will also cause weight gain.
Okay -- all that said, since you are a vegetarian, it's quite likely that you are low in vitamin b12 as well because some of the best sources for b12 are meat, poultry, eggs and some dairy. I'm not a vegetarian, but I also have vitamin b12 deficiency - pernicious anemia - and have to take shots for it every 2 weeks. B12 deficiency will cause fatigue, tingling and/or numbness in the hands, feet, legs.
I don't know how much sunlight you get, but there's also a possibility that you may be lacking in vitamin D.
In view of all the medical issues you have, I'd recommend that you talk to your doctor about getting some of them resolved. If your current doctor won't help you, you might want to find a different doctor. I'd also suggest that you check out some of the other forums here on med help as there may be others who would have some suggestions as well.
Please feel free to send me a PM (private message) with the levels and reference ranges for you thyroid levels.
You didn't mention if you do any type of exercise or not.