I'm really worried because I had sex for the first time on February 8th and my period was supposed to come on the 12th, but it hasn't happened yet. We didn't use any protection, but it was super quick, like just 10 seconds, and my partner didn't ejaculate. Plus, my hymen didn't even break. Now I'm 18 days late and I took a home pregnancy test which came out negative. I'm not sure what to do next. Could you help me figure out what's going on?