Don't know if this would help to perhaps ease your anxieties a smidgen but, for what it's worth, I had an overactive thyroid 20 odd years ago and was on medication for some years after (carbimazole was one).
I fortunately didn't have to have any goitre surgery, it was eventually "resolved" by the medication. However, the dosage is apparently notoriously difficult to get right, as mine was, and I had my medication switched a few times until, finally, the doctors "got it right" so to speak.
It took about 3 or 4 years to solve and I thought that it was all sorted until, a few years ago, my thyroxine levels were again found to be a bit "wonky". More pills, blood tests etc, and now it's supposedly okay again.
But I still have periodic tests done - just in case! Personally, I put my trust in my doctor because, basically, what else can you do?
Sorry if this is boring and irrelevant but I just wanted to let you know that I can understand and sympathise with what you're going through and hope that your situation is resolved for you quickly.
Good luck.