Hello dear I understand your concern Postinor 2 contain high progesterone and it is highly effective in preventing pregnancy as you took with in 1 hours after sex. It has just 0-5% failure rate. So your delayed period could be due to side effect of the pill as it cause prolongation of second phase of cycle. Period can be delayed by the 1-2 week. Wait for period to come. If it will delay by more than 2 week then go for urine pregnancy test and or blood HCG to confirm the pregnancy. If you will be pregnant then you can still terminate the intrauterine pregnancy by the abortion pill under the guidance of the gynecologist. Avoid stress, take healthy diet, drink plenty of water and do regular exercise. Hope this may help you Contact further if follow up needed Best regards Dr. Sagar