Bobblehead problem.
The successes you achieved through SCIENCE!! in the 'Razor, Leader of the Blades' thread back a year or so have not been fully incorporated in how you draw now, and I theorize it is because of lack of systematic attempts to 'upgrade' how you see things. You fall back to past concepts of how you should draw, ones not very well founded. Namely here, you've avoided how necks work, how ahead connects to a neck, what is the size of the neck, and furthermore, how the fabric should hug the neck and chest area. My edit below is not a c64 hi-res edit, as the 'tricks' with which you'll incorporate the advice, I'm pretty certain will come to you as you try them.
When a person tilts their head back, in order to support it, the two side tendons around the carotid naturally flare. This is an important visual clue you should give to your piece because when one sees the flared neck they can tell the person is leaning back. In your version it seems like she's a bobblehead instead.
![](http://www.productwiki.com/upload/images/dwight_schrute_bobblehead-400-400.jpg)
And this is something you'd really have to deal with, because otherwise the piece is really beautiful.
I made vartious other suggestions and alterations in the image, I'm sure most of them make sense just by looking at them, but if something doesn't, ask and I will expound.
I'm pretty confident most of the stuff I suggest here can be pullzed off, with a measure of abstraction, in hi-res. Challenge yourself more.