So I went to my post-op appointment and everything was benign, and while I could take hormones to keep things on a more even keel, I chose to just let things continue as is unless my symptoms get worse. There was no sign of cancer or hyperplasia. Instead it was termed 'dysfunction of the uterine lining', meaning the uterine wall swings between being too thick or too thin. Basically that's a fancy term for a side-effect of perimenopause, like I hoped, although given my risk factors it was good to check everything out. So, no hysterectomy or progesterone IUD required. I'm breathing a sigh of relief tonight.