Do you think she would be open to a virtual meeting with a therapist...even just a 15min consult? Maybe she'd be more comfortable with this initial approach as it could be done from the comfort of her room (or wherever) from her laptop, iPad, or phone? That might seem more low risk than going to a stranger and meeting face to face. I know my DD1, who is also 15 and sounds a lot like your DD, would probably choose that route.
Mom to two amazing DDs ('07 & '09) and a fur baby.
Gluten free since Nov '11 after non-celiac gluten sensitive diagnosis. Have had great improvement or total elimination of: migraines, bloating/distention, heartburn, cystic acne, canker sores, bleeding gums, eczema on elbows, dry skin and scalp, muscle cramps, PMS, hair loss, heart palpitations, fatigue. I'm amazed.