Take a pregnancy test! There is a good chance that you are pregnant. If the results are positive, make an appointment with your doctor to confirm the pregnancy and to arrange for prenatal care.
If the results are negative, you may have ovulated later and may need to adjust your chart. If your ovulation date is clear and you don't get your period or test positive on a pregnancy test within 18 days of ovulation, you should check with your doctor to find out what could be keeping your period away.