Your doctor is
not doing enough tests to tell what your thyroid is doing...
TSH is a pituitary test - so if that is jumping all around, it could also be the pituitary, not just the thyroid.
Combine that with your period issues, your heart, your weight gain - you need a neuro-endo and a full check up.
Always get a copy of your tests when you leave the doctor's office so you know what is going on and keep copies for yourself. Labs, mrIs, all tests - I even have my films.