Thyroid vent

So I am 35 weeks with Hashimoto’s thyroid. It’s been controlled with medicine this whole pregnancy and has been good. I’m so puzzled and annoyed because now that I’m in the home stretch and the baby has his own thyroid my T4 and t3

Levels are lower and my TSH went from .2 to 2.1 in 4 weeks. My doctor says the levels are still fine for the rest of the pregnancy but like what the heck ?? I hope my t4 levels don’t truly go too low and I start suddenly putting on pounds. I’ve been so good about weight gain this whole

pregnancy. Ugh.