TSH still rising on Propylthiouracil

So a bit of background, I am 31, was diagnosed with Graves at 26, was on methimozole for some time and went into remission. Around November of '24 I started experiencing symptoms related to my thyroid again, particularly Tachycardia, goiter & a swollen lymphnode on one side of my neck. I got pregnant despite it at the end of December and am now 15wks. At 12 wks the ran labs and my TSH came back at a .021 they started me on Propylthiouracil 50mg 2x a day. My most recent labs (blood taken last wk) came back today and my TSH is at .014. As of Saturday I feel more run down than I had before and now feel a lump every time I swallow in the lower portion of my throat where my thyroid should be. All accounts that I can find of the effects of Propylthiouracil say that it should reduce TSH by 45% within days of usage. Obviously that is not the case here. Has anyone run into anything similar where being on this medication is not leading to improvements? I have updated all of my doctors about the development and am awaiting a response/action plan.