I agree with Kelly. I had the same thoughts about the arm position and hunched shoulders. Having her lean on one arm, with each elbow on a knee and head slightly to one side, shoulders relaxed, would imply that she was deep in thought.
The stump is quite large, you could scale it down a bit. Brown will work with both purple and blue, personally, I think that you should just lighten the brown on the side of the stump so it is the color of the top of the stump and then lighten the top of the stump even more.
Also, play around with texture/pattern. Try adding the swirls, bark lines, holes to the trunk (also in shades of brown), that will tie in with the design and make the trunk look less heavy than the existing solid.
On the pants, you use a lighter blue to represent the folds in the fabric. Try doing that with the shirt, using a lighter shade of purple instead of a black lines. It will be more consistent with the design style and tie the shirt and pants together.
Cheryl