Hello dear I understand your concern If you had sex during fertile phase of period then pregnancy should be rule out. I would suggest to go for blood HCG test to accurate confirmation of pregnancy. In absence of pregnancy, delayed period could be due to hormonal imbalance, ovulatory dysfunction, thyroid dysfunction, excessive stress, change in life style in dietary habit. If period will not come in next 5-7 days, consult gynecologist and undergo reproductive and thyroid hormone analysis, USG scan, ovarian follicle study to confirm cause. Period can be induced by progesterone pill by taking for 5 days. Avoid stress, take healthy diet, drink plenty of water, do regular exercise. Hope this may help you Contact further if follow up needed Best regards Dr. Sagar