I am neither an obstertrician or an endocrinologist, so this is not my field of expertise. I do not think normal thyroid function rules out this possibility. Mostly that it may be in the low normal range, but a decrease compared to your baseline results. Like I said, this is shooting in the dark and I may be completely wrong, but I think it is worthwhile to consider.
what ever it is, I hope they figure it out soon and more important find the optimal management approach.