What Does Irregular Periods With Heavy And Prolonged Bleeding Indicates?

Hi, I have a question about my period and I'm very concerned. I'm 22 and I have had a non-stop period for over a year. I have always had irregular periods but this time around, I know it's very serious and I'll bleed very heavy for 2 weeks straight. It will go on for about 3 weeks, stop for 2 or 3 days, and continue on again. There are very few occasions where I'm feeling light-headed and where I just feel very depressed, tired and can't do some normal things like stand or walk because of very bad back pain. I ignore everything and go on throughout the day and have never gone to go see a doctor. What do you think is wrong?