Having Noticed Delay In Periods After A Unsafe Sex

Hi doctor. my gf has a symtom of late period in some months. she had last period on 27th feb 2014 instead of 1st week of february. It skipped atleat 17 days in february. We have made unprotected sex with my on 13th march 2014 in the evening time. I ejeculated in her vagina. after sex she took an contraceptive pill I forgot the name it may be I pill or unwanted 72 within 4 hours. She missed her due date in the month of march. In the month of april already 10 days has skipped she is not having her period. Her normal time with in 10 to 13 of every month. Sometimes it skips for few days. so tell me is there any chance she may pregnant? plz do reply urgently.