The way you talk about her problems will only make them worse.
You have attended to her every need you knew how. She never had a chance to learn gradually how to take care of herself. She never had the opportunity to experience herself apart from you. Her sense of self never got a chance to develope into being. All she knows is you.
All of a sudden, you demanded that she be her self (maybe due to the arrival of the sister.)
She was at a loss as how to make sense of all these, worsened by your increased demand and criticism.
Did your own mother criticise you when you were little in the same manner?
Is it possible that you are projecting the qualities that you disliked in yourself onto her?
Now, for her to regain and develop her sense of self, curb your urge to demand and criticise.
Start small. Ask her what she wants to eat, wear, and where to go. Give her all the time she needs to decide. And then cheerfully follow through. Ask about her days and what her feelings are about certain things or events. When shopping, ask her which item YOU should get.
Train her to know what she wants and think of herself as deserving. Train her to express her desires without feeling guilty. Train her to be assertive with polite phrasing. For example, if she likes a toy, say: "I like it, too. But I need you to convince me to spend the money." Have her place orders in restaurants. Have her help with chores.
Expand her horizen, both in time and space. Have her learn more history, the ancient Romans, Greeks, and statesmen of the past 200 or so years. Read the children's version of the Bible.
Keep praising her. Give her the space she needs to grow (i.e., make it less about you, more about her.)