JM27746,
Congrats on your decision and your progress to date!
I'm going to remind you of something obvious that you already know.
1. Addiction is a lifelong struggle.
2. Even though you have quit the amphetamines, the underlying problem they were intended to treat still exists.
3. It will take time for your body to adjust, but it WILL adjust.
No, I don't think you have permanent damage. Yes, it will be harder to lose that extra weight.
I hope you are doing this with the help of your Dr.
I have long said that the body produces energy in the amounts required of it. If you sit in a chair all day for a few days, you'll begin to feel tired all the time.
If you are up and active, your body will provide you more energy to accomplish the physical tasks being required of it. Of course, this takes a little time for the body to make the adjustments, but it will.
Being active will also help you burn more calories and this will help with your wt gain issue.
When I say up and active, I don't mean you have to go to the gym and work out all day or even every day. Just being up walking for 20 or 30 minutes each day will help. It should be a brisk walk.
Good luck on your continued recovery.