Please help me!

I'm 16, I've been with my fiancé for over 2 years, we have sex quite often and he pulls out and is positive he didn't in or near my vaginal area. (I know this is true because I always finish him off with my hands and then swallow). We are not TTC at all!!! I was supposed to get my period about 2 weeks ago and I still haven't gotten it.  I have been told by several people that being active in sports and stress cause fluctuation within getting my period and causes the cycle to be missed or late sometimes. Is this the case??!! I pray so because I can't be pregnant!!! Please help me