What Causes Irregular Menstruation And Cysts?

I am 26 yrs old,TTC, till now there is a folicle every month ®ular menstrvation,there is no folicule this months, but on 16,17th day there is abnormal bleeding,then doctor prescribed meprate 10 mg for 10days. abnormal bleeding stopped.though no menstrual periods on 35th day,again abnormal bleeding ,then doctor found a small cyst& prescribed ovaral-l...what is happening i am bothering abot this.