Okay, there are often longer waiting lists if you are relying on school to assess.
Have you requested assessment through GP or paed?
Ds wasn't dx until late.
Dd sounds as though she has hugely low esteem and has developed this attitude to protect herself against academic work. Ie she has convinced herself she can't cope and this is a coping mechanism.
I would say GP, paed and camhs referral.
It's really hard when they have got this far without support, as now hormones and independence mean they have to be the ones to agree to everything.
Would she see the doc? Does she see any of this as a problem? There are support groups for teens with add/ ADHD. But really important to get her properly assessed first, I think. Doc might have other ideas. She sounds as though the attention side is what is causing her problems, and everything else has been built up to protect herself, but I would not rely on school to get the ball rolling. Waiting for the EP is like waiting for Christmas, except usually it takes longer than a year.
Start reading up on this stuff. You can often implement some strategies before dx that help.
And get her on some decent omegas, zinc supplement, and Epsom salts in her bath as an interim measure. (Assume you have not tried, yet?) School actually asked us if we had medicated ds when he had been on that regime for a week as he was a completely different child.