Hello dear I understand your concern Missed period after unprotected sex moat commonly by pregnancy. Pregnancy is possible because you did sex during fertile phase of period and there is slight penetration. I would suggest to go for urine pregnancy test and or blood HCG test to confirm pregnancy. If pregnancy test will come negative then no chance of pregnancy. In absence of pregnancy, missing period could be due to hormonal imbalance, ovarian dysfunction, excessive stress, change in life style and dietary habit. Period can be induced by progesterone pill in absence of pregnancy by consulting gynecologist. 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