That's a pretty nasty wound. You need to start some antibiotics for her.
Also, if possible, I would soak the wound for as long as possible. Gentley wash the soaking wound and try and get some of the black dead tissue off. Trim away the feathers so nothing touches the wounds and keep her in a clean cage with towels. It sounds like you are doing everything to help her. The maggots can't breed in the wound, so there is a finite number of them. You'll get them all eventually.
Also, if possible, I would soak the wound for as long as possible. Gentley wash the soaking wound and try and get some of the black dead tissue off. Trim away the feathers so nothing touches the wounds and keep her in a clean cage with towels. It sounds like you are doing everything to help her. The maggots can't breed in the wound, so there is a finite number of them. You'll get them all eventually.