Hi and thans for the query, Lack or a missed period is a female of reproductive age deserves a former exclusion of a pregnancy. Its important you did a pregnancy test already. It might be important however to redo the test using blood sample (beta HCG in blood measurement) or be patient and redo this test in a weeks time. It is however not unusual to experience a delayed period in some females. Are you experiencing any signs of prominent menses or signs of pregnancy (tense breast, nausea, vomiting, excess urination, lower abdominal pain, nausea etc). I would suggest you take your proper pregnancy test again, and consult with your gynecologist. Thanks and best regards, Luchuo, MD.