Hallow Dear, You are indeed in a very tricky situation. Unwanted 72 is a fairly reliable post coital emergency contraceptive pill. You had unprotected sex on 14th and 15th. You mentioned that she has taken Unwanted 72 within 72 hours of the sex; however, the million dollar question is after which intercourse? If the pill was taken within 72 hours of 14th and 15th both, then you are protected from both the sexual intercourse. However, if you had taken pill within 72 hours of sex on 15th which falls beyond the sex on 14th, you are not fully protected from pregnancy. Anyway, since her next menses were due on 18th of this month, your both the sexual intercourses were beyond the fertile window. So the chances of pregnancy are very less. Please note that after taking Unwanted 72, her following period may get delayed by few days to a week or so; you need not get panicky. If she misses her period for more than 8 days, you may perform pregnancy test on overnight morning first urine sample; earlier, the test may report false negative results. I am sure, this clarifies all your doubts. Dr. Nishikant Shrotri