ovulating but still not pregnant????

All of my tests are showing I did in fact ovulate this month and last month. My LH was high when it needed to be, my ultrasound showed a 17mm debris filled cyst so my RE said that means I ovulated probably only a few hours before my scan. She said it was probably around an 18mm follicle and then once I ovulated only hours prior, it turned into the 17mm debris filled cyst. If it was a simple cyst, then it would of proved I didn't ovulate. 21 day progesterone was 8.8. Everything I'm reading is saying different levels but mostly a 10 is normal but my RE and my regular endocrinologist both assure me anything over 5 means ovulation. I guess it's just a difference in opinion in doctors but my debris filled cysts also proved I ovulated. Anyways, husband has great sperm counts, tubes are not blocked. I know I CAN get pregnant because I had an ectopic in May 2016. It was just a fluke thing because again, my tubes are perfect according to my HSG. Anywho.... so why am I not pregnant? Is it poor egg quality? Is that the most logical explanation????