How long does it take for a half Asian half white 15 year old female nose bridge to grow to get rid of the epicanthal fold?

Nasal growth is not going to get rid of epicanthal fold. If you want to get rid of this fold it can be removed without difficulty. Nowadays, Epicanthoplasty is performed without worrying about the scar and I perform this procedure about 50% of Asian Eyelid Surgery.

At fifteen years old, you can't expect a lot of nasal growth, especially if past menarche. Additionally, there would be little impact on your epicanthal folds.if your eyes cause you distress, discuss this issue with your parents and together you can decide if some type of intervention is right for you,

This is an interesting question but my assumption is that if you are 15 years old you can't expect much if any change in the height of your nasal bridge or the appearance of your medial epicanthal folds.  I can't be sure since there are no photographs nor have I examined you but I wouldn't expect much change in the next few years.  Your Eyes and nose will look different as you age but The specific anatomy your asking about probably will not change significantly.Chase Lay, MDAsian facial plastics specialistDouble board-certified facial plastic surgeon