Missed Period Defined

So i just found out something. We all may have been doing this wrong!!!

So today i found out the difference between a late and missed period. Late is 5 or more days from your expected period. A MISSED period is 6 weeks after the start of your last period. Meaning us counting DPO n stuff doesn’t always mean anything. Really we should project 6 weeks from our last period and then test 5-6 days before that which probably means about a week or so after our expected period. Hmmm 🤔 very curious.