You control the hitter by getting ahead, attacking their weaknesses and changing speeds.
You hear it all the time: Slow her bat down with the change up! Well, you don’t really slow her bat down physically but you do mess with her ability to launch! If the hitter is thinking change-up, then she is not going to be able to take the same aggressive swing.
Mess with her timing and her head. Change speeds often, early and in tough situations!