worries about pregnancy

hi, my girlfriend and I recently had sex, latter that week we were mucking around and we had unprotected sex for about 1 minute (in which i did not ejaculate), We were worried about pre-cum causing pregnancy so she took the morning after pill the next day (within 12 hours). Recently she has said that her breasts are sore, and last night had nausea (but didn't throw up). Its been about almost 2 weeks since the incedent happened. What are the chances?