I’m confused

So I had sex a couple weeks ago and it was protected but he took the condom off so he could ejaculate on my back but I felt it drip down my back to near my vagina, I freaked out after it happened but I knew I was going to be fine. Because of the way sperm is supposed to travel. Yesterday I got my period again. I started my period 12 days earlier than I should have. I took a pregnancy test and it came out negative, so I’m just trying to figure out what’s going on😩