Period CM??

Hey 👋🏽 so my period was supposed to be due this week, all of my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period apps</a> say I’m five days late but I know I’m only one day late as it is CD 40 for me today my last period came CD40 and the period before that came CD39 so I’m thinking maybe this one will come CD 41 since it seems to be going up a day each period. But anyway, I’m a little thrown off by the CM I have it’s fertile cm very stretchy but not clear it’s very bouncy and can roll up into a ball. I’ve notice fertile cm this entire week every time I’ve wiped. Is is normal to have fertile cm when your period is due?