So I'm far from being good at pixel art. I like this piece mostly because you did shading way better than I ever did on anything, so take my comment with a pinch of salt. But I tough I might be able to help out a tiny bit.
One of the two things I noticed was that the head was pointed down at a slightly weird angle. I assumed it's because the piece was supposed to be pretty dramatic but just to see how it looks I rotated the face forward and raised it a bit to add more dimension to it. I also colored the neck using colors on the face so it stands out less. It doesn't look that well since I didn't redraw it in that pose, rather just cut out and rotated, so judge the difference of that on your own.
The other thing I did was to cut out your back. There's definitely too much of it on the image, it's hard to tell where are your shoulders located because of that. Case is however, it's supposed to represent you and if you have a bad posture I guess a bit of the back could be seen from this angle. I choose to go all the way with it and just cut as much as I found reasonable to straighten it out.
I assume the art is based on a photo of yours. If you still have it and don't mind showing it, it would help out to see how exact the drawing is.