It doesn’t seem likely that you are pregnant if both pregnancy tests were negative. Lack of menstruation is the first (but not a secure) sign of pregnancy. Delay of your menstrual period can be also due to the existence of a functional ovarian cyst. Functional ovarian cysts are typical for women your age. Functional cysts produce hormones that delay the period. They usually persist for 2-3 months and then vanish spontaneously. At the conclusion of an ovarian cyst episode, women usually experience a heavier period. Ovarian cysts can be diagnosed only with ultrasound scan. You can visit your gynecologist if you like or you can wait another 2 months before making a visit.