Being deprived of a relationship with a primary caretaker for 19 months does have effects on a child. It is hypothesized that there is a change in the brain that occurs causing behavioral or developmental problems. Children in foster care or orphanages are left with feelings of anger that they do not understand and cannot verbalize.
You can do 2 things:
1. Accept her unconditionally despite her behavior. (Which I am sure you do)
Boundaries and rules should be set but avoid isolation and physical punishment which may trigger thoughts of earlier treatment.
2. Get professional help from a therapist who has knowledge in Reactive Attachment Disorder. You may be able to get a referral from a agency which places children in foster care because of neglect
. She may need this special approach due to being without a primary caretaker for so long. The special therapist will be able to help you find ways to manage her behavior.
Her behavior is not that she does not understand. It is her way of expressing uncomfortable emotions that she cannot verbalize. The child therapist will also work on helping her verbalize her feelings.
In the meantime, when she "acts out" try saying, I can see you are feeling very (angry, mad or upset). Notice her response when you acknowledge her feeling. It is ok to follow up with, I know your mad right now but the rule is "no throwing things". I think you need to go to your calm place for a few minutes. Pick a "calm place" that is nearby and not isolating. Some children who have trouble regulating their emotions really like a small nylon child tent as a calm place. Instead of punishment, you are teaching her self-regulation.
Hope this helps and good luck.