Ugh why

My period goes from super heavy and I do have to go to the hospital to the next month being absolutely nothing I'm 18 and I have a very good sex life but this has been going on since I was 7 (when I first started) my OB put me on birth control but it didn't help once she took me off I barely bled for a year lately it's been the heavy to the point I've been in the hospital the past three months. They say it's nothing can someone help?