Hi,
Periods can be whackey and irregular during certain times of your life; it's especially common for younger women & perimenopausal women to experience this. Stress, medications, rapid weight loss, etc., can also effect your period. Try to relax and not think about it; the more you stress out about your missed period, the longer it may delay it. Since you've never had sexual intercourse before, missing one period isn't a big deal. If you start missing your period on a regular basis, you should seek advice from your doctor ~ the doctor may prescribe oral contraceptives (bc pills) to help regulate you.
Take it easy :)