Is it possible you have fibroids and/or are going into pre-menopause? Sounds a lot like what my mom dealt with when that was the case for her. They lasted long times but went longer and longer between until stopping altogether. I'd recommend going to see your gynecologist. A simple blood test will determine if you are in pre-menopause, and an ultrasound can reveal any fibroids which might be adding to things.
Unfortunately, heavy and/or prolonged bleeding are pretty common in the years leading up to menopause since you are not ovulating regularly. Birth control pills are commonly used to level out the hormones and regulate the cycle. If you do not want to go that route, prescription strength NSAID's or Rx Lysteda (tranexamic acid) can be taken during your periods to reduce flow. If you have fibroids (common benign uterine growths) they could be contributing to the heavy bleeding. Fibroids tend to have a growth spurt shortly before menopause but then typically shrink shortly after menopause.
The biggest risk of all this bleeding is becoming iron deficient. So watch for symptoms of that (fatigue, weakness, dizziness, pallor, shortness of breath) and take an iron supplement (preferably along with vitamin C) if necessary.