What Causes Heavy Bleeding During Periods For The Past Four Months?

I am suffering from heavy bleeding during my periods.I am 36.I am unmarried.For the first time i had sex with a guy.After 15 days i got my periods flow was heavy.After that i didnt get my periods regularly.I had little spots daily.I consulted a doctor she suggested me ovaral l.The next month i got periods but heavy flow then she gave me menoguard to stop heavy bleed .For the past four months i am suffering from this help me.