When did I conceive ??

This is actually a little embarrassing. I slept with two guys around the same time, and I’m 14 weeks pregnant today. My last period was August 11. But they said my baby is 5 days ahead? Which is confusing. So when would my conception date be? (I’m due may 17) slept with man 1 in end of July and man 2 in August. But since I’m 5 days ahead is that normal??

Also I took 2 pregnancy test back in August 2/3 before my period and they came out negative. I was just wondering if there was a possibility.