Cadet Kelly (2002) on Netflix

Fourteen-year-old Kelly Collins lives in New York's Greenwich Village, is hip to the latest fashions and has never been more popular with her friends. Things are great - until her mom marries the head of the George Washington Military Academy in upstate New York. Kelly relocates and is ordered to turn in her designer duds for the fatigues required at military school. Free-spirited Kelly makes an effort to blend in with her by-the-book peers, but finds herself at odds with her ill-tempered Cadet Captain Jennifer Stone, who sets her sights on breaking in the newest cadet, but Kelly tries to prove that she is tougher. As Kelly endures rigorous boot-camp training and even a court-martial at the hand of her own stepfather, she begins to see the value of the military life - especially after she makes the academy's distinguished drill team and impresses Cadet Major Brad Rigby, the cutest boy in school.