My Appy is very sensitive to leg pressure, as well; it doesn't take much at all to cue him off the leg...doesn't mean he always does the 'right thing' off my leg necessarily, but he is always intune to my legs, which is nice.
If you want to get her used to you 'moving' your legs on and around her, I would simply sit on her, perhaps have someone hold her, and just move your legs back and forth, so she understands that not "all" leg movement is a signal to move. I do understand where you are coming from, and she does need to understand that that not every leg movement means to move forward. I've had to practice this with my App too, because he would just 'shoot' forward as soon as I got on, and was situating my legs on him...so I would halt him and ask him to stand, while I moved my legs around. He eventually caught on, and it hasn't dulled his responsiveness off my legs while riding, but has shown him that he doesn't 'have' to dart forward just because I touch him.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."