Confused

I am wondering am I pregnant or is it stress related. I had unprotected sex on the 13th and 14th of this month. My last period was on the 19th of July. My Cycles are usually 30 days long but I also have irregular cycles. I had sex on low pregnancy chances days which were cycle day 26 and 27. So am I pregnant or is it stress or is it because of my irregularity. My period is just 2 days late but it has happened before but that been a while ago.