Would a breast reduction be beneficial to my daughter?
Ideally a reduction mammoplasty is to be done when the person has completed growth. Performing surgery at age 15, while she is still growing may cause the breast to enlarge again. So ideally you want to wait till she is 18 and the growth of the breast has stabilized.
On the other hand if the enlarged breast is a hindrance socially and physically, surgery can be done.
Another option is to do liposuction to the breast now, let the growth continue and by age 18 she can decide along with her doctor what she wants. These decision are made after in person examination and talking with the minor for suitability of the procedure.
3 years after her first menstruation or period regularly every month, she will be able to perform this procedure to avoid those symptoms and get a better shape on her breasts and a nice profile.