When we work at incredibly small scales, as you can imagine, there is very little room to do very much. If we try cramming in too many details into a small sprite, its difficult to read your sprite. I think there's a good reason why small sprites avoid realistic proportions but are usually very chibi; putting in less important details is kind of silly when they can easily distract from more important ones.
If we go for something chibi, of course, we will greatly exaggerate the head and eyes so they are easier to make out. That along with the mane are things that makes a given character recognizable. If you ever get deeper into pixel art, you will have to be comfortable with the idea of tossing out details that will not fit in a small scale.
Overall, a piece that had a bit of potential. This may be one of my harsher crtiques, but I just can't agree with the approach that was taken. You're likely going to like the results from going for a chibi body style.