Color count could come down by quite a lot, I imagine. You have quite a few near-black colors and a lot of the skin tones are really similar and could probably be merged with no detail lost. Also, on the color chart the 2nd row, 2nd and 3rd column, those grens could easily be merged. Perhaps even the 1st column could be merged with those also. Basically, this could be taken down to 16-20 colors, I think, but it's not a necessity.
I think her boobs get mixed up with her knees. At first I couldn't tell what was going on there, until I thought about the foreshortening consciously. It's especially difficult for my mind to understand what's going on with the left (viewer right) breast and leg. I'm not sure how that'd go about being fixed, though.
Interesting piece though, I don't see pixel art used like this too often.