Could I be pregnant?

Me and my friend were messing around in a field, and while we were, he stuck his penis inside me. I kept saying no, but I was too weak to do anything. He said he pulled out, then came, then after he came, he stuck it back in again. That was my first time, and I'm terrified I may have gotten pregnant because he didn't wear a condom. I want to buy the pill, but I don't want to waste money on something I may not need. Help!