RAI kills the thyroid. It is the same isotope that high Iodine levels in bread around 1960 was put in place to prevent the thyroid from absorbing. The theory was that if the thyroid is full of the good iodine, then it can't absorb any of the radioactive form, 131, such as would be in the fallout of a nuke. My guess in your case is that since you are so high in Iodine and tsh is low, even if an MD with a death wish for your thryoid gland were to inject you with a typical dose of RAI, it would have little of its intended effect;;; since tsh is low, thyroid is being commanded to take a break and not to make anymore t4.
I think what typically happens is those who succumb to the suggestion of RAI get their thyroids killed by the RAI, and the rest of their lives they become dependent on pills like armour and synthoid. I'd almost bet that if you stop Iodine and drink plenty of fluids things will trend towards "normal". Eating goitrogens like cabbage, broccoli, cassave etc. could hasten if the literature I've read is correct, which considers them iodine antagonists.