Her left arm is greatly misplaced and oversized especially on the armpit part. Bad eye foreshortening. Add more curve to her body for extra sexiness and feminine look. Don't be too shy (or don't be too "proud") to use reference.
it's okay, try to find a reference after you transfer your mental image to the paper / canvas. It doesn't have to be EXACT reference, you can find body part by body part or by reading anatomy books and theory. Reclining pose is one of the hardest pose to do, btw. Old masters has many works of reclining pose.