Have you considered laparoscopic surgery for endometriosis? Many OBs/fertility clinics poo poo this option because they want to go directly to ART, but if that is not working for you, worth considering. You would need to find a place that truly specializes in endometriosis/unexplained infertility. Check out Center for Endometriosis in Atlanta GA. Many success stories coming out of there. Years ago, I had booked my surgery date with them when I found out I got pregnant naturally. As I recall, they said they would basically look through your entire reproductive system, flush your tubes, clear anything that may cause adhesions, etc. From my experience, if you and husband had the whole fertility workup and everything is fine and you are ovulating (confirmed via ultrasound scans, this is important), it is most likely endometriosis.