eight sprite-a-bit

[StarSock64]

 
The art shows that Pearl's upper body makes a really specific shape and doesn't really look organic. I think that you should try to replicate the slanted rectangle shape that she has going on, rather than attempt to sprite what you think of as a body's form.  For starters, I think the body you have needs to be thinner, and the...boob cover part? is too high up.

You've also got the wrong angle on the arches above the star on her not-shirt.
You've got it sloping up and left, away from the star for a long time before the downward curve toward the arm begins, and you used lines that are more angular.
In the official art, the arches are more like curvy Ms. The arch should curve above the star and quickly slope downward, all the way well below her armpit. Note the way her body interacts with/attaches to her arm in the official design.

Also notice that in the art, the area around her shoulder is a little wider, but her arms taper and become quite thin. You kind of have her whole upper arm looking a bit thicker. I think her legs may need to be a bit thinner too.

You don't seem to have her proportions down quite right. Her torso should be teeny...not just in terms of being skinny, but I think it needs to be shortened height-wise too. If you look at her official design, her torso is rather short, and her legs are loooong. In your sprite, the legs and the torso are of a fairly similar length.

Hope that helps