Great composition of this shot. So difficult to get the light/shade/contrast right - and you did very well indeed. I certainly feel she is waiting for something - but what?
Well it's not the most cheery photo I have ever had to critique, but here goes :)
As "theshrew" says contrast was maybe a little tricky here, but I agree you have it quite well.
However I personally would have cropped the photo less. I would have liked to see all the head for instance.
But over all it's a decent shot.
Well done, Brian