Can't See The Shadows

I'm having trouble applying the shadow work to this sketch: I didn't draw the figure to be fleshed out with shadows. I find that sometimes I draw things for their line, and this figure is definitely one of those. As I fleshed her out with shades, I found the figure just awkward. Even the profile wasn't made to be given dimensionality - it was always about the line. So I'm struggling finding the shadows for this piece.

Plus repeating sketches and constantly changing them when you think they're done, well that kind of anti-climactic activity isn't easy to jump into. Ah well...