Just that really. I'm really bad at knowing dates - like when my period is due - and doctors seem to expect me to know the exact dates of previous periods. I never do - and I always end up very roughly guessing... with an accuracy to within 4 weeks.
I presume every other female must track their cycle in some way? If you're one of these people, how do you do it? Do you mark it in your family calendar in sparkly golden ink? Or do you use an app?