PREGNANT OR JUST STRESSED

anon
on october 1. i had unprotected sex he ejaculated outside of me. on october 7. i had a normal period. throughout oct. i felt fine, just gassy and stressed. this month is the first time i've tracked my period. it's now november 9. and my period didn't come on the exact day as last month. could i be pregnant or just scaring myself? i don't know much about the mestrural cycle. how should i calm myself down? my boobs are sore