Seems like they have packed out to the point of being too big. Go to a bootfitter, they are the only ones who can help you. Not a bunch of 12yr old armchair ski experts.
Length of the bit really is determined by the thickness of the ski. The diameter on the other hand, is determined by the ski material. As a general rule, if the ski has metal in it, use 4.1. regular wood core, 3.6.
Again that is just a general rule.
Girls training for top level gymnastics are built like men. Thats why the younger the girl, the more potential for gymnastics. Prior to hitting puberty, the body structure is almost identical to that of a boy.