Morning After Pill & pregnancy

I recently had unprotected sex on the day of the ovulation/day after the ovulation. I'm quite worried that I might be pregnant, but a friend of mine told me that since I have taken 3 morning after pills in the last 6 months (3 in my entire life) chances that I'm pregnant are really low... I didn't take another pill this time because I'm afraid a 4th one might be dangerous for my health. Does any of you know if the amount of hormones of those pills actually inibits my ability to conceive?