What Causes Delay In Periods?

About 41 hours after having sex I took plan b. I had unprotected sex the night of my last birth control pill before my sugar pills. Unfortunately, I didn t take that last pill before my week off when I m supposed to have my period. The whole prior month I haven t missed a pill. Fast forward a couple of days, I was supposed to get my period yesterday and nothing has come yet. I have had a decent amount of white, thick discharge and don t know what to do. Could I be pregnant or is my period just delayed because of the medication? I m just looking for some insight on other cases possibly and when I should start being concerned.