American Congress of Obstetricians and Gynecologists (ACOG) says that you need to take your teens reports of unwanted hair and acne seriously as these conditions can be associated with medical problems and long term poor psychosocial problems.
The diagnosis of abnormal hormone levels can be made by speaking to your gynecologists or measurement of serum androgens.
It is not clear that polycystic ovary syndrome (PCOS) can be diagnosed in adolescent girls within 2 years of menarche; thus, this diagnosis can be given prematurely and needs on going evaluation.
Treatment of acne and the unwanted hair (hirsutism) is still important
Pelvic ultrasonography and blood hormone tests may be confusing in teens and not necessarily needed.
The finding of polycystic ovarian morphology on ultrasonography has a prevalence in adolescent girls of 30–40% and alone is not predictive of the presence or future development of PCOS.
The most important strategies for teens are lifestyle changes, physical hair removal, and androgen suppression or blockade with medication that slows or prevents new hair growth.
Hormonal therapy, including BCP, may take 6 months before benefits of treatment are seen. Because of this you should have your teen seen at regular intervals to make sure she is on the right therapy.