Hello, Thanks for posting your query here, I m Dr. Remy, I have read your query and I can understand your concern. From what you have described, It is highly unlikely for you too get pregnant provided you have taken your morning after pill within 72 hours. These pills acts by preventing the fertilization of the ovum and also the implantation (the embryo sticks onto the mother s womb). Neverthless, there is also a 5% failure risk, which may happen if fertilization has already taken place. In any case, Just to reassure yourself, I would suggest it would be best to get an urine pregnancy test done a week after your missing periods. The morning after pills contains a high dosage of progesterone hormone (which is in fact 10 times that of the normal oral contraceptive pills). This hormone levels may cause the irregular bleeding or the delay in your periods. Excess stress also may cause this delay. So I would urge you to stay calm and relaxed, so that your body takes its time to tune back into its normal path.. Hope I was able to answer to your query, Kindly revert back to us for any further queries. Thanks and regards