If you can get to a drugstore, you should be able to pick up a pregnancy test kit, and then you'd know. But I don't think you could be pregnant, with what you and the bf have been doing. http://www.emedicinehealth.com/home_pregnancy_test/article_em.htm
when you worry that your pregnant, your body tricks you into thinking it. You can actually CONVINCE yourself that you might be pregnant, and because of stress, etc, you can actually miss a period. Im sure its nothing. Relax love!!!