Change in AF? This is not my usual AF

This was the first month off TTC. We BD 3 days and took 1 day break BD 3 days 1 day break etc. starting a little before my predicted fertile week, during my predicted fertile week on my predicted fertile day and a few days after. AF was due yesterday there wasn’t really any sign of AF coming then this morning I woke up and had the brown discharge like I usually get at the end of AF. My usual AF come on hot like bad cramping super heavy bleeding but this has never happened. Has anyone else experienced a change in AF when TTC or during the first month of TTC?