MAKE YOUR WHOLE PICTURE YOUR BUTTON:

Below...see how this is accomplished
Note:  In order to get the whole picture on the button, I have added background at the top, bottom, and left side.

In addition, I had to recreate part of
 left arm of the girl on the left and add part of  a shoe on the middle girl.
FINAL RESULT:

Everything shown within the
Blue dotted lines is on the top of the button, everything
Home.
Buttons.
NEXT.