hypothyroidism and period

I have hypothyroidism and since I was disagnosed and treated w medication I’ve noticed that my periods are inconsistent and went from a 30 day cycle to a 39 or greater. My obgyn did not seem to think it was related but I certainly do. I want to just stop taking this medication and go back to my normal cycle because I want to conceive. Has anyone had a similar experience w their periods or have stopped medication? A