could i get pregnant?

i had unprotected sex Wednesday night at like 11 and then early in the morning at like 7 at the time it was like 18 days before my next period if my period is on time and im not stressed . today friday December 15th i went to go pee and wiped and had a very very light pink color on the toilet paper and the hours after and thursday i had extremely bad discharge what could be going on ? could someone help me ?