Plastic surgery shouldn't be undertaken lightly whether by adults or legal minors. Having said that, people achieve maturity at different points in their lives. Some 25 year olds are less mature than some 16 year olds.
On a case-by-case basis, especially if there are actual physical findings that correlate with the patients' concerns, and if the parents are supportive, surgery can be considered in a legal minor.
Examples--often a rhinoplasty is done in young women once they are "skeletally mature" around age 16. I have performed breast reductions in young women because of the significant lifestyle and health burden posed by excessively large breasts in a 17 year old.
Seek the evaluation of a thoughtful surgeon, and discuss it with your family.