Too much thyroid support is a stressor for the adrenal glands.
Thyroid energy in excess of what the adrenals can handle is a stressor to the adrenals.
Quacks on this forum? Hmmm . . .
You did not take all that much iodine - no more than the average Japanese takes daily. If you left out the vital co-factors, especially selenium, and weren't also getting plenty of good antioxidants in your diet (or supplementation) you were not doing yourself a world of good to be sure.
Lots of things generate free radicals, but that does not make them bad in and of themselves. Oxygen for example. The key is balance - and often taking a single item without supporting items in your diet or supplementation is not balanced.
A couple of Standard Process items you might consider are Drenamin and Thytrophin PMG - both very high quality, usually highly effective and made by no one else.