Chances of being pregnant?

I lost my virginity to my boyfriend a few days ago. We were a little tipsy so I'm not quite sure how safe we were. He was wearing a condom but I don't know if it broke or maybe if he put it on wrong although he's very sure it was all set. A few hours later I bought plan B and took it within 12 hours of having sex. Is there still a good chance I could be pregnant? I'm not on birth control.