Is Pregnancy Possible Post Intake Of Morning After Pill?

Hello. I have been told that I am the father of an unborn child. Using online calculators and the LMC (12th Nov) and due date (19th Aug) the conception date is the 25th or 26th Nov. However, I did not have sex with this girl until the 1st or 2nd Dec. The first time we had sex she took the morning after pill (at least I think she did), and after I didnt ejaculate inside her. Is it possible that I am the father? And if so how likely?