First, post at original resolution! Makes it FAR easier to edit.
Second, if you're going for a more realistic style you might need to put some work into learning anatomy first.
It can be slow going, but if you need a quick and dirty method the anime building-blocks method can help as a stopgap.
(also, to embed click the mona lisa icon on the left and stick the url between the two bracket tags!)
Adviceways, think about your proportions more. She's got a big head and tiny noodle arms, spaghetti legs, and a diminutive tube pasta body. Try to match those proportions better, either by making the head smaller or the body bigger!
You can also get away with not having much of a face, many pixel artstyles convey faces through single-pixels for eyes. Starbound is a good example for this art style, and I've seen even smaller styles forgo faces entirely. Experiment, and play around with google! You can find EXCELLENT resources there! I frequently search up pixel art with a variety of other things ("dog," "Castle," etc) simply to find new things to try!