My girlfriend and I had intercourse on 12/11/17 at around 10pm and her period started 12/7 lasted 3 days. We had unprotected sex and I tied to pull out before ejaculating and I think I was successful as there was a lot when outside of her. However I can not be sure. She took Plan B one step around 6:30pm on Tuesday 12/12/17 however before taking the pill she had some light yellow/clear discharge and after taking the pill the same thing. Is it possible this is some semen of mine or is it ovulation or just cervical mucus? We do not want a child right now.