I know this may seem more credible coming from a doctor than one of your friends or family, but your chances of being pregnant with two negative tests and regular periods after one protected sexual encounter are really virtually impossible. Seeing a doctor for a blood test for pregnancy might ease your mind because it is more accurate than home tests, but I am more concerned about your inability to accept the reassurance of your own body telling you that you re not pregnant. If you are not mentally prepared to deal with the anxiety about the possibility of pregnancy, then it may not be ideal for you to be sexually active until you can come to terms with that, or perhaps starting on a more effective contraceptive you can control yourself (like birth control pills, etc.) may make you feel more protected. You may also have other issues that make you feel this way- you may feel guilty about having had sex in the first place, or other anxieties that your doctor or a counselor may help you address. I hope this is helpful and good luck.