I normally have pretty irregular periods. I can go for up to 10 months without having a period. I started my period on the sat/sunday and it is now a week and a half later and it is still going. I'm kind of worried because this hasn't really happened before. I have been to the doctor a few times about my irregular periods and they run tests but nothing ever comes up. I don't want to go again for them to tell me everything is fine.

What could this be and should I go to the doctor?