Okay, so my redlines suck. Because we're sort of... on par in our talents. But It made me understand what I was seeing.

You see, you've got her back twisting. But you don't have her hips following. That's the problem with the hips and the legs. So I've angled her butt. And that fixed that problem, sort of, and so you have to change her legs a bit too.
Also her torso is really too long, but that's a stylistic choice so I ignored it.
And the problem in the shoulders is just that you didn't bother to visualize the way a shoulder works or connects to the body.
You should've drawn a straight line across (or in this case it would've been an oval now that I think about it).
I did a very bad job of redlining now that I think about it....
Um.. Anyway. I hope I helped a little.