Longish just need some questiond answered

Okay so I'm gonna break this down I had sex 10/17 yes is was a green day but I got my period 11/2-11/6 or at least I believe it was my period. I have not had sent at all since that day in October and now my period was due 11/30 and didn't show it usually comes a day before glowd predicted and has never failed me but now I haven't gotten my period and I said it was late and it pushed back to the 12/2. And no I haven't been stressed lately life's been pretty great just got my CNA and an awesome job and my son is health and happy. My questions are this:

1. Is it even possible I could be pregnant?

2. How is that possible?