Hello dear I understand your concern Pregnancy is not possible in presence of the period. Again you have negative pregnancy test does not indicate pregnancy. Your delayed period could be due to the hormonal imbalance, ovarian cyst, endometriosis, excessive stress, change in the life style, thyroid dysfunction. I would suggest to consult the gynecologist and undergo investigation like reproductive and thyroid hormone analysis, USG scan, ovarian follicle study. Treatment will depend on the test result. Period can be regularize by birth control pill. Avoid stress, take healthy diet, do regular exercise and drink plenty of water. Hope this may help you Contact HCM for further health query Best regards Dr. Sagar