Hello.
I, personally, would find out how the Dr came to this conclusion and if I did not get the answer that I was looking for, I would get a second opinion (either see a another Endo or ask for my general Dr’s help).
I’ve read here in the forum that TSI, TSH, fT4, fT3, and TPOab tests are needed to help decide if you have actually gone into remission. I might be wrong but definitely TSI, TSH and fT4. Signs and symptoms are also important. It could be that your heart has been affected permanently and therefore the tachycardia and “never feel good” symptoms and now you need to see a cardiologist but you might also want to find out how your Dr is deciding that you have gone into remission.
Wish you the best finding out what is going on. Hopefully someone with more experience can provide more input for you.
Caro