My Period Is 3 Days Late. I'm Sure That My

My period is 3 days late. I'm sure that my period is regular, for I had observed it for almost 2 and a half years now. Im expecting my period this December 18, yet it doesn't came until now. I had my last period, November 17 (first day). I had a sexual intercourse last December 3, and it is unprotected but he told me that he doesnt come inside me. Then, on December 5, i started taking pills. While taking pills, I had sex last December 10 but he withdraw it, same with last December 16. Is there a possibility that I am pregnant? Because my period is 3 days late already from the date that I expected it to came and I don't know what to do anymore.