PCOS - bleeding everyday?

i dont normally write on anything like this but i really cannot take much more i bleed everyday and have done for like 4 years (with a 2 week gap here and there when the drs have given me pro vera or northisterine to stop the bleeding) but as soon as i stop taking the pill i get so much pain and bleed heavy again, i am now anemic from the loss of blood, i have had ultrasounds and a biopsy and all clear. They diagonosed me with PCOS. I am constantly back and forth to the drs and feel like they dont believe that i am bleeding. I once ended up in hospital due to the amount of blood i lost and they sent a message to the drs to refer me back to gynae which i had already been dismised told to lose weight. The drs referred me to an endocrinogolist which sent me for another ultrasound which came back clear again. I am trying for a baby but feel like i have no hope as i dont even know if i can ovulate! has any body got any ideas as to why i dont stop bleeding yet nothing is wrong with me. Ive never heard anyone else to bleed everyday and the only way to stop it is for a week or 2 with tablets!:( Surely something is wrong, could they miss something like ovarian cancer?