Prayers for you. I had my TT done almost 14 yrs ago. All my graves symptoms went away, and I did NOT gain any weight. It will take a while to get your dosage right afterwards, but like i said, all the symptoms went away. You can not even see my scare from it. Just make sure you faithfully take your medication.....
Good luck....
It's ok to feel scared, we all were when we had to have ours out too! Let's hope it goes well for you and you recover quickly. If your medication is right to start with you shouldn't put on any weight.
Good luck.