Hello and welcome – We’re fellow patients here, but hopefully, you will get some additional responses. I’m not familiar with balance as a typical post-RAI issue, so would suggest reporting this to your doctor. Hopefully, others will chime in here as well. You can also join our Facebook group (go to Facebook, search for @GDATF, and then click “Join Group” in the top right-hand corner of the screen. That group is much more active than this one right now.
As you noted, it can take some time for the RAI to do its work, but if you start to feel hypOthyroid symptoms come one (fatigue, weight gain, cold intolerance, constipation, etc.), before your next followup appointment, definitely let your doctor know so that you can get labs done.