I have had the same problem for years. the pill helped me regulate, but each time i try to go off of it, i will go months between periods, and then have periods that last 2-3 weeks if not more (one lasted 7 months) they are exactly as you describe, just heavy enough to need a tampon or pad.
I know that the pill helped me a lot with this, they were completely regular, but any time I go off, I have no idea, they're awful. ...
Anyone have any ideas for either of us? I personally have been to the doctor and their only answer is the pill which i don't want to be on because i'm trying to get pregnant, obviously not going to work if my dumb period won't stop...