It really doesn't matter much one way or another. You can't really make yourself look older simply with a pulled up hairstyle! It is a common trick used in movies that the spinster wears a bun, with glasses, to look unattractive. But the man takes the glasses off, pulls a pin, and her hair falls down, and she is gorgeous! Doesn't work that way in real life.
Dress and act professionally. They know how old you are. There in no way to trick them. If you look younger, so much the better. If you act younger too, that is not so good!