Try using the Tiny Tot HUD. It folds your torso down to create smaller than the default size 0 sliders allow you to be. It allows you to choose your size between 1-10 (1 being tallest, 10 being shortest).You can use any animations with it, just be sure to pick up some free alpha masks to hide the folded part and prims over most of the torso. Nor sure if this helps at all but worth a shot. Oh and if you want to see it in action, just IM me.
this is the girls version but there is also a boys version as well as a light version.
https://marketplace.secondlife.com/p/Sweet-Baby-Tiny-Tot-Reducer-of-Avatar-Size-Toddler-Avatar-Tiny-Avatar/1230204