Hello, Once you go off the pill,it is a big switch for your hormonal system of your body. It may take several weeks  before your period finds it natural rhythm. Depending upon the woman, the type of pill, and the length of time you have been taking it, it may take anywhere from several weeks to several months before hormone levels regulate and allow regular menstruation to resume. In addition, if your periods were irregular before taking the pill, your periods may continue to be irregular after stopping the pill. In addition current state of your stress,your body weight and any other illness like polycystic ovary disease,also makes a difference. Generally, your period should start four to six weeks after taking your last birth control pill. If you have not begun menstruating after three months, you may have a condition called post-pill amenorrhea. Birth control pills stop your body from producing hormones that trigger ovulation and menstruation. When you go off the pill, it can take a while for your body to re-adjust to its natural hormone production schedule. Eventually though, your regular menstrual cycle will return. If you don t get periods even after 6 months,then you would need  consultation and examination by your Gynecologist. Thanks