I'm scared.

according to the app, I had unprotected sex when I was fertile, but he didn't ejaculate inside me. also my last period was on the tenth.. my cycle ranges from 28 to 35 days. my last period was on December 10th. I have slight cramps sometimes, usually when I pms I get a lot more and sore boobs but now I'm feeling nothing and my period is a day late. this is all I can think about and I am so scared, please help.