Is she landing or getting ready to spring up? You've done a great job with the anatomy but it's a little weak in the dynamic department. Take me with a grain of salt since I'm used to seeing superheroes in really distorted positions (see Aeon Flux).

She just landed and is ready to attack by throwing the chakram.

I totally agree, there is something lacking. I loved the legs but I feel I can push more with the arms and torso to get a really awesome look. I wonder if having her lean more forward would help?

There is something off about her hips...I don't think she's got any...

also, your thighs are different length and the extended one is thinner than her calf....there also a lack of butt (which goes with the hip thing)

the legs I know how to fix but...how do i fix the hips?

hip bones are the key I think...when I get the hard copy I can redline for you ^_^

like Blitz, I'd say legs and hips. myself, I would add a pronounced fold of flesh above the rim of her leotard, on the right, where the skin would actually fold a bit following the pose. also, I would thicken the upper legs by at least 50%, pronounce her butt with it, and even out the underline of it on the right. it's a mistake I used to make myself for many years, along with adding muscle bulges where I should not. :P
the upper arm on the left needs more mass. the right one looks alright, pose, too. the neck is a bit thin, I would try and shift the left line a bit more left and more vertical. or try if you can't follow the lines created by muscles and sinews of the neck musculature there.
the chakram looks good to me, although with me it would look like the hubcap rim of a '64 Cadillac. then again, I'm an automobilist, so sue me. :)

as for dynamics, I would try and lift the edge of her cape a bit with the same wind that ruffles her hair. try lifting the right corner of it, following the line which starts at her shoulder.

I hope that helps, with Blitzens redlines.