6 Days Late and Negative Pregnancy Test But No AF

StarDust
So of course I did something dumb. I had sex on what was supposed to be day 24 of my cycle, and the guy came inside. I waited in anguish for my period to show up but it didn't. So I purchased a Clear Blue Plus pregnancy test and the result was negative. Is it possible that stress and strenuous activity could have made it delay or something else ? I'm really worried