Work on the back arm. It looks like she leads with her hands. Try and close the gap so that her hands and elbow are aligned with the shoulder as they pass the shoulder. So the hands are neither in front nor trailing. So start by closing the hip/back elbow gap using the rear shoulder. Then use your hands. Take a look at what these guys are doing with their back elbow and see the alignment hands/elbow/shoulder. Just work on that for awhile and continue to use the legs. and Go NorCal
Best MLB Swings-Slow MO - YouTube
Good advice, IMO.
Another way to describe it is; keep the hands back and let the body rotation move the hands forward, not the arms. Don't pull or push the bat with the arms. Let the body move the bat, and the hands throw the barrel.