Let's make sure you understand the goal: You are trying to develop a good 18 YOA pitcher. You are not trying to develop a great 10U pitcher.
Your DD's body is going to change dramatically in the next 2 to 3 years. She is going to develop a bosom and her hips are going to spread. If her pitching form that you are developing now is wrong, she will have to learn a whole new pitching motion when she matures, and you will have lost 3 years of work.
At your DD's age, you have to focus on mechanics over speed. After her body matures in 2 or 3 years, then you can worry about developing speed.
Your DD's body is going to change dramatically in the next 2 to 3 years. She is going to develop a bosom and her hips are going to spread. If her pitching form that you are developing now is wrong, she will have to learn a whole new pitching motion when she matures, and you will have lost 3 years of work.
At your DD's age, you have to focus on mechanics over speed. After her body matures in 2 or 3 years, then you can worry about developing speed.