Don't finalize this adoption until you're sure you want to do this. You may love this child, but if you can't live with her if she doesn't change, it might be best to let her go.
Is it possible for you to not work for awhile? If you got a good attachment therapist and spent some serious time working with this child, at her age, the prognosis for healing is very, very good.
You might want to check out the support groups at
Welcome to Attachment & Trauma Network* - ATN