Sorry this sounds stupid🙈

Me and my partner are trying for a baby. And there is one question that keeps nagging me after intercourse. Sorry for the next bit it's abit cringe 🙈 but how long after sex do I stay laid for his sperm to stay in me and not run out to have a better chance of getting pregnant.  Feel like if I get up after 5-10mins it's running out of me 😕