Could she get pregnant from this?

Stupidly, I ended up having sex with a girl last night, without a condom. She told me I should take it off, and I was thinking with the wrong head and did. Although I did not *** inside of her, I have heard pre *** can get a girl pregnant, but only if there is, I guess "left over" sperm from a previous ejaculation. I jacked off at about 5:00 P.M. and I showered at 7:00 P.M. Ended up having sex at around 12:00 A.M. I was drinking, so I pissed quit a lot. Do you think I should be worried? Is that enough time to get all the previous sperm out?