Models do things that normal people don't do. This particular one is lifting one knee to lower the edge of her pelvis, while simultaneously twisting her trunk. This presents a chest-waist-hip ratio that is more athletically pleasing, but which reminds me of an explanation for ballet; contorting your body into unnatural positions and making it look elegant.
There is a specific visual hip-to-waist ratio that the human mind finds most pleasing. Women, due to a fluke o bone structure and center of gravity, can cat their pelvis in ways men cannot. This allows hem to present the visual of that ratio by emphasizing certain parts o the bodyŚ and yet in your skeleton, the pelvis line is almost completely horizontal.
Looking at her spine, she is compressing her lower back, the lumbar. She has a bit of swayback going on, pushing out her rump and pulling back her shoulders. It makes the Hiney appreciatively round, and destroys her posture in the process. I see this partially reflected in your skeleton, but. I can't tell how integral that line is.
Her feet are arched the wrong way; if you look at the picture, the inside arch of her foot traces a half-circle, which emanates from the ground. It is, literally, an arch. Think of it like an organic spring plate that is a half-circle. The foot "flattens" when it hits the ground, but springs back to it's curved shape when not forced flat.
I only go into this because your illustrated foot curves exactly the right way, in exactly the wrong direction.
Breasts should not be accounted for in the design of the torso; you should instead draw their Ribcage, and "attach" breasts to the outside. Otherwise the torso will be blocky, and it will show through.
I suppose that exhausts my immediate supply of relevant commentary ^^"
sorry, but I love the human body, and having an eye for doodling, I have found all sorts of tidbits that get me looked at strangely at dinner parties.
But I'm only half as perverted as I seem! I swear!
And heck, ballpoint will teach you feel, going with the grain, and "oh $%*& I can't erase can I?", which is a hard skill to learn.