The way the light hits the shoulder area and then abruptly stops implies something strange about her physique. I would stick to lighter and middle-value tones and then go easy on the shadows, as they should only be emphasizing the form, if I understand your lighting situation.
There should be a cast shadow coming from the left breast, as well.
You need to clearly define her hands and feet. They seemed to have been forgotten about as you started putting the finish on the other stuff.
I would suggest sketching out everything clearly, and to the same level as everything else in the drawing. Don't isolate one or more areas and only work on them, but rather work on the whole sketch evenly.
I hope that you find that advice helpful.
"Try not. Do or do not!! There is no try"
-Yoda, The Empire Strikes Back
It looks like the light source is pretty much over to her right side, around head level. Considering that, it seems like that highlight on her left shoulder/armpit shouldn't be as harsh or large as it is. Also in your last iteration, you've shaded all under her right breast... I would think the light coming from the side wouldn't create that sort of downward shadow.
As well, her right ankle should be more fully lit from the side. And her knees seem a bit too prominently highlighted.