My 11 yo DD has had her pitching coach for about 2 years now with regular weekly lessons since the beginning.
Finding the right pitching coach is a very difficult task. My DD is 15 today. Pitching since she was 8. We used one guy in our area for 3 years or so. He was where she started and he was a successful Canadian ball player. Taught an open style and a follow through across the body not up on the right side. That was good. This was before we learned the concept of internal rotation on this board. For a variety of reasons we left him and I was essentially her coach for 2 years. I took her to 2 different female pitching coaches during that period and left both because of some of the mechanics they were teaching. ie follow through at the right shoulder, walk through the pitch at the end, open style, etc. This year we found another woman who pitched and now coaches. She too teaches the follow through to the right side shoulder. I basically told her going in that we would not do that and that my DD follows through naturally where ever it goes. We agree to disagree on follow through. She also has her do a drill at the start in which she has her flip her the ball using the fingers with the palm facing the catcher. Another waste of time but it's a few minutes. After that, we get to pitching and she has helped there. My DD was swimming alot and she was also not bringing her glove down correctly. I knew this but it was good to have a coach who could tell my DD the same things. Lastly, she has been able to teach the spins and footwork for different pitches (screwball in this case). So it's been valuable. Guess what I'm saying is it's not impossible to have a coach that you don't necessarily agree with on all points if you are gaining value from the coach. If you feel you're getting no value, it's time to leave.
How much break time have you allowed her in those two years? Maybe she doesn't need a pitching coach at all right now if she's doing well on her own.