Hallow Dear, Chances of conception due to sexual intercourse on the day 6 of the menstrual cycle are very very remote since on that day the egg is not released by ovaries as yet. You had taken Postinor 2 which is a post coital emergency contraceptive pill. It is known to cause some withdrawal bleeding few days later, which you had. Moreover, these pills are known to delay the following menses by few days to a week or so. It seems your menses are delayed due to these pills. These pills are very effective in preventing pregnancy if taken within 72 hours. You consumed it within 24 hours. So for practical purposes, you need not be worried about pregnancy due to this sexual act. Urine pregnancy tests may give false negative results if performed too early. Hence, if your menses are delayed for more than a week, then you may repeat pregnancy test on the overnight early morning first urine sample. Alternatively, you may opt for Beta hCG test on the blood also. If your pregnancy test after a week is negative and still you do not get menses, you may take some Progestational preparation like Deviry for 5 days; you will get withdrawal bleeding after 4-7 days. I hope this helps you. Dr. Nishikant Shrotri