period 1 day late

Elizabeth
So basically I'm a very paranoid girl lmaoo and I had sex with my bf about a month ago. We did NOT have sex to the point where he would cum 
He took his penis out way before hand and I gave him a blow job for about 3-5 mins. Then he cummed and it went all in my mouth 
So I am certain that no cum went inside my vagina 
I also know that there was no sperm in the pre cum because he did not cum before having sex with me. 
I am almost certain that I'm fine, I think lol.
So my period is a day late ?
But last month it came on the 19th and I usually get it on the 20th 
And now that it's the 20th I've got nothing yet
Maybe my stress caused it to delay?
Help lmao I'm freaking out