What Causes Heavy Bleeding During My Last Menses?

last month i got my period 20 days lately and bleeded heavily, to stop bleeding my Dr adviced me to use regestrone tablets 2tabs for 5 days and 1tab for 10 days.My bleeding was stopped.She adviced me to use krimson35,i am going to get married and should not increase weight.Pls advice should i use this or the problem exist again.I am not having pcod.pls help...............