I had hypothyroidism at first then developed graves disease just as I was doing my 4th stimulated cycle 2 years ago. I felt dreadful, sick and agitated, lost weight but put it down to the different IVF meds I was on, then I put it down to morning sickness. A few weeks after I got preggers I saw my thryroid doc and she picked up on it. I went on some meds and got it under control. Pregnancy apparently puts it into remission and it hasn't come back yet but I go in every 4 months to have it checked out, plus I am on meds for a slightly underactive thyroid now
Stimming doesn't seem to interfere, I feel fine now and my levels seem to be ok.