Okay I Used To Have Periods That Would Stop For

Okay I used to have periods that would stop for 6-9 months and my dr would put me on Provera. This was when I was 16 I got my period when I was 15. So it was still getting regular. Now as an adult (21) I'm bleeding all the time. 3 months at a time. I just had a exam done, no bleeding today. But the obgyn said "yeah I do see some blood" he was looking at my cervix correct? Shouldn't that have been cause for concern? I have a period and then bleed off and on for the rest of the month the week before my period It stops. Intercourse is painful. A lot of pain in general. Since I bleed all the time, it hurts a lot. Sometimes its blood clots sometimes just spotting. I'm starting to believe I have cancer. My dr said the bleeding was normal and I need birth control. It's pcos because of my 16 year old history of periods.