Ovarian cysts.

I have had an abnormal menstral cycle since I was in the 7th grade. I am now in college and it is getting worse. I have pain during intercourse with my boyfriend and I only have my period once every 2 months for 4 days. The doctors think I have cysts but every time they go in to see, they can't see any. Help I'm getting sick of being in pain all the time. I need advice on how to catch the cysts before they go away.