I had sex and the condom "slipped off." I'd had a lot to drink and realized what was happening... I think right when it happened... but I can't be sure. I do know that we stopped and he did not ejaculate inside of me, but there may have been precum. At first I didn't think I had anything to worry about, and then I freaked out and bought/took Plan B 26-28 hours later. The only symptom I've had so far are tender breasts, but they felt that way during/after sex and continued to feel that way, each day less so. It's now been about 2.5 days since the incident happened. I'm supposed my start my period within the next week or so, so I don't think I was ovulating.

Has anyone had a similar experience to this and can offer peace of mind?