I have been experiencing the same! I was on birth control for years and I finally got off 2 years ago last August and my cycle hasn't been normal since! I never know when I am coming on and never know when I'm going off. I always figured that my body was trying to catch up and get back on the normal 5-7 day schedule with my cycle because I never had them when I was on depo, but now I'm convinced it's something else. I started my cycle around July 15th and I am still on! Bleeding very heavy at that with blood clots! I may go to bed one night and use the bathroom and think that I am off of my cycle (but still where a pad to bed), but wake up the next morning to find that I am actually still on. This is very frustrating!