How to help a teenager with GAD

I have a 14yr old who was diagnosed with GAD when she was 10. She has never been medicated other than when I've had to call the police on her (paramedics had to sedate her). That sounds horrible I know, but she also has PTSD and ODD and those 3 don't mix! After the diagnoses she was taught strategies to help get over the anxiety she would experience. Now that she is a teenager I find that her needs have changed and the GAD has gotten worse. She is so hypervigilant about everything around her. She can be called a name by someone and it sends her in shut down mode. Near the end of school last year, the school had to call the police and paramedics because she had locked herself in the bathroom and was curled in a fetal position in a stall.  After that she wouldn't leave the house.

The dr's haven't wanted to do long term medication therapy as they say not enough studies have been done on the long term effects on children and I don't want to medicate if I don't have to. Honestly is scares me. Are there any suggestions on strategies that I can try with her? Puberty is hard as it is, but when there are mental health issues involved it makes it all the more challenging!

PS we have tried counselling for many years even before diagnoses, but she isn't open to it at the moment.

Thanks

Tanya

She did do group therapy numerous times. Her longest stretch was for about 9mths when she lived in a Pre-Adolescent Treatment Program. She also has been in a children's pyschiatric ward a few times and did group there. But the longest she was in one of those was a month. She is withdrawn in group but is open in one on one counselling. Though when she does one on one she talks about herself in the ways of how important she is and doesn't talk about her problems. It's like she is embellishing on things  to make her self esteem better, if that makes any sense.

Her mental health issues and past trauma have made for a complex child that I don't know how to help sometimes. And honestly, it seems like she gets put on the sidelines when her sister is ill. Her sister's illness has involved many hospital stays so I feel like I haven't always given the attention that my oldest needs and that I am sure doesn't help with her anxiety.

*sigh* if only parenting was easier.