I would recommend calling the crisis pregnancy line at 1-800-712- Help or going to http://www.optionline.org/ and finding a center in your area. They can give you a free and confidential pregnancy test, and in my experience they are super nice, with unplanned pregnancies in their past too. At 15 it can be normal to have a late period, but it also can be a sign of pregnancy. I would go to a pregnancy center either way to discuss the whole pulling out method. Anytime you have sex you have a chance to become pregnant, no matter what you are doing. I do encourage you to wait to have sex because of this. I myself had sex at 16, thought I was pregnant, and it honestly changed my life. I didnt want a baby at that age, and I decided to wait until my wedding night some day in the future. It wasnt super easy to do, but let me tell you from someone who did it both ways, it was so amazing that we waited, and to this day 4 1/2 years later I feel like her really respected me and loved me enough to value my body and wait for me. I cant tell you how amazing that is/feels, but I promise its worth it!!