I'm into this so far, Janel. I think you've already nailed what's up with the anatomy, but I'll put in my nickel's worth, if it may help to clarify.
Yes, the spine and musculature of the back is not described here. Handling the reflective light subtly will help explain the angle of her backside relative to the torso. Make sure the reflective light stays cooler than the light plane flesh tones. Neutrals are always a good standby for this kind of thing. And by "subtly," I mean keep the values compressed so the shadow plane on her back stays in shadow.
One thing you mentioned was the angle of her leg going toward the knee. I'm not getting the foreshortening, yet. Watch the structural connection where the hip flexor meets the quad (top of thigh). Making that planar change more obvious will help with form. Also, check your width of the knee relative to the thigh in your reference. It seems like it's narrowing too fast. When the knee bends like that, a lot of muscular material gets compressed and folded up, so it adds a bit of girth to an otherwise bony area. Also, get some reflective light up into the underside of the thigh using the ground color. Hue shifts in reflective lights allow the subject to fully connect to their environment.
Oh, this may be extraneous, but I think it's worth a mention: Watch the chroma in the ostrich feathers. Too much of that indigo, and it draws more attention to itself than the figure.
Your skin tones and the softness with which you're handling them are really great, so I'm confident you can go the distance on this one. Keep going!
[Kim, you know it's not the fumes - it's the booze
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