Welcome to e-health. I had a total hyst. I wasn't put on anything though. I do use some natural alternatives like Black Cohosh and soy milk and other soy products.I'm not a Dr. so I can't tell you if it is causing your symptoms or not. The Black Cohosh is supposed to be good for those symptoms you mentioned though. It's for PMS or menopause.
I found this site that might explain a bit about HRT.

Let us know how you are doing. Good luck.