I too have been on HRT, but was prescribed unopposed estrogen, I have extremely dense breast tissue as well, and have had a bad mammogram result, pleomorphic calcifications (was told that hormones increases risk of breast cancer). Are you having regular mammograms? If not, please do so immediately. I had no idea about any of this and was shocked to find out that I had been taking a medication that can increase my risk to breast cancer and the OBGYN set up a mammogram immediately and sure enough, it came back bad. Please make sure that you are ok with hrt, I have heard that when you have dense breast tissue it is harder to read a mammogram so make sure that if you get one it is a digital mammogram, the breast surgeon I have seen said that it is always a good idea when you have dense breast tissue to always go digital. Good luck and please have a mammogram once a year or every six months as long as you are taking HRT. I am not a doctor, but have had some negative results with HRT, wishing you the best and keep us advised as to your status.
Sorry I am too new at the hrt thing myself. I have just been relying on my doctor to tell me what is best for me.