Alright; I'm not the greatest, especially with people, but to a good extent I know my way around some shading and at the very least, theory.
A lot of your shading in the nude picture was good, but the torso kinda stood out to me. Your lighting on the torso seems a little more all over the place... so I showed you what a cross section would look like with your shading... in the red box. In the green box, I have taken a cross section of what the torso would look like with my style of shading.
My fix doesn't look the best, I don't have a photo editing program on this PC, so I did it in paint, but you should be able to get the jist of it.
Your shading is whats going to give the allusion of shape, contours, etc.
I know the human body isn't a perfect oval, but what this is showing you is that you need to soften up your shading... in the middle of the torso, you have a very distinct line in the darker and lighter sides... that's pointy. Soften it to smooth the shape, it'll look much better in my opinion.