late period from paranoia ?

Okay so I had sex about a month ago. 
It was not full sex to the point were he has to pull out and cum.
We were humping in and out for like 5-10mins? And then he took his dick out we talked kissed etc then I gave him a blow job. After the 3-5 min blow job he cummed and I swallowed the cum.
So I know no cum went inside my vagina 
And I don't think he cummed before seeing me! So no sperm in the pre cum
He's experienced in sex and knows what he's doing to avoid any type of mistake 
It was in a moment hype and we didn't use protection but I know in the future since we are in a relationship and will be having sex often.
I think my stress is delaying my period, but sometimes it comes a day before the expected date that's what happened last month? So my stress and the new spring weather change could that delay it
I'm just kinda worried because I over think 
I appreciate the replies thank you