My guess is that you've showed her nothing but love, both for her brother and her. And you've showed her that in your family, you don't give up on someone who goes through difficulties.
Whatever feelings of being slighted now will be understood as she gets older. Or not. If she's anything like you, she's an empath, and she knows your heart.
What kind of lesson do you think you would have taught her about life if you had been less devoted or indifferent to her brother? Your actions spoke louder than any words could have.
She's lucky to have a man like you for a father.