well there's five major spots you'd need to fix to get the anatomy straightened out. balance, the positioning of the 2nd leg, the impossible wrist position, the chest, and the raised arm. and while i admit, my own grasp of that is far from perfect, i figure i could offer some advice.
Firstly, Balance. the character is standing on one leg, yet said leg is off center.
if you've ever looked at someone standing with only one limb touching the ground, watch their hips. they instinctively shift their balance to get that leg as close to center as possible.
next is the other leg, bending the way it is, the knee either needs to dislocate, or be on the side. straight on just doesn't work.
then we've got the wrist. your wrist can only bend 50-60* before it has to twist to go further, yet you've got it going almost 90* with no twisting visible. redrew that.
next is the chest, this is the easiest bit to fix, i just widened one side to accommodate the fact that the spikes being centered and straight forward means you're looking at her head on, not slightly off to the side like the reference you were using was.
and last is the other arm. the underarm should be smoother since it's stretching, not constricting in this position, and the hand works better in a position that shows fewer fingers. also the elbow being straight on makes more sense than side on from the posture.
lastly, when cleaning up the lines, don't be afraid to redraw or resize sections that look off. the first pass is almost never correct.
