Double check. I would confirm the negative result with a blood test from a reputable lab, like your doctor or Planned Parenthood. If your period is like clockwork, you may be pregnant, or something else may be going on, depending in your age and other factors, like stress. .
As . As doctors, anytime a fertile, sexually active woman has an abnormally light or missed period, the first thing we do is rule out pregnancy. You may have taken the home pregnancy tests a little too early for them to be very accurate. A home pregnancy test is only 97% accurate if taken a week or more after the missed period. You may want to take another to be sure. The cost shouldn't matter. Reasons for a missed period besides pregnancy are stress, poor diet, extreme exercise, weight loss, hormone imbalance such as with thyroid disorders or polycystic ovarian syndrome and even peri-menopause if you are older. If you have a positive pregnancy test or continue to have missed or irregular periods, contact your doctor to discuss.