He doesn't need to worry about you on Mother's Day as you are not his Mother (and if you are.... eeewwww).
I'd just be concerned that he remembers you on your birthday. If he does get you something for being the Mother of his children... that is just a bonus (IMO).
And regardless I wouldn't remind him... I would just wait. And if he screws up! You have a whole year to lord it over him and make him feel guilty.
