Overthinking?

So I had unprotected sex for the first time ever and I’m not on birth control. He had ejaculated before and did not clean it very well before doing it. He did the pull out method (100% sure) but I keep thinking if there was any pre-cum. Also I was on the day 23/28 of my cycle and I’m usually VERY regular, so the chance of getting pregnant was low. Should I be worried?