About month ago my girlfriend and i had unprotected sex for less then 20 seconds, i didn't ejaculate inside her but i've been reading stuff about precum and i getting a bit worried.

I had ejaculated was 12 hours before we had sex, i took a shower and made sure i cleaned my penis  and pee'd since then. Also before we had sex i wiped the tip of my penis with tissues incase there was already any precum...

I've asked my gf if she's been feeling any pregnancy symptoms but she said no, but im a person that gets worried easily so i just wanted some opinions... What are the chances of her being pregnant do you guys think?