Should I be concerned ???

I had unprotected sex sometime towards the end of August but it was only for 3 minutes tops. I didn’t get a period June, got it July 3rd, and then August 10th, but the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> app says I’m 2 days late. I understand having sex there is a possibility I could be pregnant, but should I really be concerned since my period isn’t regular? My boobs are bigger, and I have had a cramp like pain in my stomach which started Saturday night.