Can Postinor 2 Cause Delay In Period?

Hi Doctor, i took postinor 2 for the first time 38 hours later after having unprotected sex. after about 5 days i started to frequent the wash room, and also had slight vaginal bleeding, my breasts became tender and these dissapeared after afew days. what is worrying me is that av missed my periods by 5 days now, is this an effect of the drugs or are they signs of pregnancy