Congratulations with your pregnancy! Very few doctors will approve Iodine supplements, and even fewer know that the TSH tests doesn't show the right picture.
I would probably not tell them at all, just go by symptoms and general well being, but thats me. When one feel great, keep up the work!
Only recommendation I can give is to take selenium with your iodine, and do read / study. I took a lot of supplements in my second pregnancy; vit C at least a gram. He seemed to be much better off than my first one. Still regret that I didn't take Iodine and magnesium. But I didn't know about it back then.
Suggestion; search Violien`s posts at this forum, also stopthethyroidmadness site. They give explanations about the TSH rollercaster.
Best of luck:)