Should I be worried about getting pregnant?

I had unprotected sex last Friday, the last day of my period, he didn't use a condom and although i was on the pill, we were drinking and i had been sick earlier that day and may have thrown the pill up (i take it at 830pm). is it possible for me to be pregnant? i also took the emergency pill on the sunday after wards.. just wondering what the chances are as i also have PCOS (poly cystic ovarian syndrome) which means i rarely get my period anyway..