I would definitely ask the doctor again, just to be on the safe side. But it is possible that with your level of intervention already (meds, whatever), combined with your level of illness, and added to the fact that you are listening to your body and not pushing things right now, that your doctor is OK with whatever you are doing. I would, indeed, get it nailed down, though. Being hyperthyroid can throw the heart rhythm out of whack, and exercise makes that a more dangerous possibility. Also, there seemed to me to be a problem with muscle biochemistry while I was hyper. The muscles didn’t "recover" (for want of a better word) as quickly from retracting/working. Pushing them caused strains and shin splints.
Wishing you well,