help with strange AF

ladies,

My "period" came very late on 18dpo ..

usually LP is only 13 days..

I have endometriosis so usually painful and heavy periods..

but the issue is, my period is so light, it's barely there when I wipe.

besides that, it's not heavy at all or painful like always.

I'm starting next dose femara today as I'm ons cd3 but this period has me.worried.

what can be the problem and how will it influence my cycle