My best friend always forgets my birthday. Then she remembers a few days after and apologizes.
Queenie, she manages to remember other people’s birthdays that she hasn’t known as long or as well as she knows me. Why can’t she remember mine?—Forgotten friend
Probably she keeps a reminder of the birthdays of people she does not know as well as she knows you, but assumes she will not need to be reminded about yours. Try dropping a slight hint when your birthday is approaching. And for her birthday, you could give her a set of “belated birthday” cards to use “as needed”.