I guess you would not be scared but for the fact that you had some kind of sexual exposure. Having an intact hymen does not stop sperm from getting in, same way blood can come out. You are not listing any other early signs of pregnancy so the chances are high that stress or a hormone upset is causing the delay. Run a home pregnancy test to ease your mind. Sign up with your local friendly gynecologist for your annual exam and meds to jump start your cycle. Good luck!