Look, you're obviously very bright but I understand your situation can feel like competing in a marathon with ankle weights.
My research focuses on T3 and T4 -- have you tried high dose iodine and selenium supplementation? Also, celiac disease can sometimes only present symptomatically in the thyroid -- have you tried eliminating gluten from your diet and increasing your intake of MCTs? Some dietary experimentation may help your case.
In the interim, just focus on the fact that you are where you are. Very few people on earth have the mental capacity to even be accepted to medical school and that places you in very selective company. I'm sure you are leaps and bounds ahead of most of your high school and undergraduate peers. Act with confidence, and study with confidence. When your perspective on the situation changes so will your performance.