Suggest Medication For Irregular Periods

Hi, my age 23 and i'm unmarried..i have a late menses problem since last 1 year...i get period with 2-3 months gap everytime since 1 yr...but i can see the symptoms of menses every month like blood mucus, back pain etc..but there is no normal 5 days bleeding...recently i consulted a gynecologist...she concluded that my problem may be due to over body weight, as i increased 8 kgs in the last 1 year duration and suggested me to take regestrone for 3 days..i took the tablet during i have light bleeding while passing urine lasting from before 5 days..after 1 day i took the tablet, even the light spotting, blood mucus also stopped...i want to know what if the tablet is taken during period? what may be the solution for my problem?