Hello THanks for writing to us with your health concern. An absence of periods indicates that there is something wrong with your reproductive axis. It would generally indicate a difficulty in getting pregnant. After birth control use, rarely a condition called amenorrhoea results. This is because the hormones get disrupted. This is quite rare, but should be ruled out in your case. Also, intra uterine infections or damage to the endometrium ( lining of the uterus ) can also lead to absent periods. Please visit a gynecologist. Get the following hormone levels measured - FSH, LH, serum estradiol, Progesterone, AMH. Get yourself tested for uterine tuberculosis ( if it is endemic in your country ). Also, go for a pelvic transvaginal ultrasound scan and an internal gynec check up. Since you are bleeding in response to the Plan B, it appears that this is most probably hormonal imbalance. 3 months of cyclical progesterone therapy might jumpstart your cycle. Do not ignore the absence of periods, seek treatment. All the best Take care.