Hi For Some Reason My Monthly Period Is Delayed For

Hi for some reason my monthly period is delayed for 4 days now , may 5 was the first day i took Althea Contraceptive Pills until now, and I haven't missed any day of taking my pills. I did not have sex for 7 days after the first day i take the pills as per the direction written on the box of the pills. May I know the reason why I'm delayed? Is this normal? Am i pregnant? if so, should i stop using the pills?