I just went through my calendar to see if in any of my cycles my luteal phase was longer than 13 days. And there are none however my cycles fluctuate between 26 and 36 days over the years. I know the luteal phase is usually pretty fixed but all of them at 13 days or less. Not a single one over 13 days?

Can someone help me understand? I’m sure I’m just not understanding the prediction but I’d like to.

How do I know if my period was late in past cycles?