Late period!

Demi

Hey everyone! If anyone could give me advice that would be great :)

So I have been on bc for four months now and during my placebo weeks I usually don’t start my period until two days in but this months placebo week I am currently four days in and haven’t started my period yet.

I do have a boyfriend but always take the pill correctly.

Is this normal, can it possible to miss a month or should I be worried ?