If you had unprotected sex between Days 10 to Day 20 of your cycle I.,e between January 3rd to January 13 chance of pregnancy depends on when you used the i-pill. It should be used within 72hrs of unprotected sex .If after 72 hrs , you had unprotected sex again during the fertile period of your cycle I.,e, any time between day10 to day 20 of your cycle, there is chance of pregnancy.All the above is applicable to regular menstrual cycle of 28 days.