I've had the same problem, apart from mine is a different story. When I first started having periods I would go months at a time without any and when I did they would only last a day or two, then I had two normal periods and after a week of the second, I started bleeding constantly for months at a time with only a few days break, a friend persuaded me to get the Contraceptive Injection, which I did but I found out I was 7 weeks pregnant when I had it. It caused me to miscarry and I carried on bleeding constantly. I saw the Doctor and he put me onto Femodette but I found that although I had bigger gaps inbetween my periods, I was still having too many and whenever I bled I got migraines. I went back and they put me onto Cerazette and after a month, I've stopped bleeding completely, which is what's supposed to happen. Seeing a doctor is DEFENATELY a good idea.