Hello, I have gone through the query and understood your concern. Firstly, let me inform you that you had the intercourse during your safe period and did not need the emergency pill in the first instance. Presuming that you have a regular 28-30 day menstrual cycle, your ovulation would have fallen around the 7th of January. Since the sperm can remain active for up to 5 days after ejaculation and the ovum remains alive for 24 hours after ovulation, any unprotected intercourse during this period can cause conception, which you did not have. The emergency pill gives adequate protection when consumed within the stipulated time interval. As it contains high dose of hormone, menstrual irregularity can be expected. Your next natural period may get delayed by a week or two. Please restrict the use of the pill to one or two occasions per year. See a specialist for further support if you become overdue by ten days. Hope this helps.