late period heLP

Had my wisdom teeth pulled out and had anesthesia/a bottle of pain killers/ a bottle of antibiotics in December, also dry humped with boyfriend in boxers and me in a thong but swallowed the load, and am stressed about being pregnant and finals. Could I be pregnant? I'm sort of late but I'm waiting to see if my period comes by the end of January to freak out. 
Posted this earlier ^^
Update: there's a spot of light pinkish reddish in my underwear. Is it implantation blood or the start of my period??