What Causes Delayed Periods After Having Anal Sex?

I feel so stupid right now! I was in the moment and had anal sex :( I haven t broken my hymen yet but I have missed my period this month and I can t be pregnant! I can t tell my parents I have never had sex in my vagina and it was a just in the moment thing ! Please help me please! I m so scared and I ve heard that It can dribble down and stuff and go in and I ve had my period since the summer of 2014 and I ve never missed it and I just want to know if I can be pregnant or not