I think this is beautiful. Now if you're looking for an anatomy perspective, the only thing I would say too look out for is her shoulder and lower arm. I feel as with the shoulder needs to be brought out a little more along with the size of her head.
This is always a big stump in any artists practice, is keeping it steady with proportions. Either something is too small, or too big.
Seeing as you have a picture, take the picture into a different program / print it - turn the picture around, flip it - keep an eye at how far away certain things are to the body. So for instance, how fair away is the hair from her chin? How far the shoulder? Hows about how big compared to her chin on the picture?
Remember to keep changing around the picture - (upside down, flipped on a program, angled) anything to keep your eyes ready to any disproportions.
With that said, for what you have done, you did a beautiful job portraying this girl. Her eyes and lips - the face seems to be the huge vocal point as well as that arm, so with the face done so nicely it really brings it out!
If you can fix that arm a little, It'll bring it out even more.
Very nice strokes in your art as well, such things can help get the viewer into your picture and can tell them how the object (this girl) is portraying herself (what is sticking out like her cheeks and or her hair)
Keep up the beautiful work! You have a wonderful sense of style.