Why is my period taking longer to arrive?

Bex

I'm on Rigevidon (no placebo pills just a week off) and up until a few months ago, I'd finish the last pill on a Friday and get my period Sunday evening. Now its not arriving until at least Tuesday/Wednesday.

Why is this?

What if it just keeps getting more and more delayed to where its starting when I'm about to start the next pack?! 😩