Kind of going off what Zane said.
Her feet look off because they aren't in perspective. You have her body in two-point perspective, but you left her feet on the same plane instead of receding into the vanishing point.
I don't think there's really anything wrong with the arms, not counting the lack of hands, but the torso is pretty off. You have this bar of abdomen that separates her chest and her hips, which completely removed the hourglass shape. Not all women are super curvy, but you gave her a large rib cage and large pelvis with no connection between them, which is unnatural. I think that's the biggest thing that makes her look out of proportion.
Little things :
In your original sketch of her build, it was a little off symmetrically. The left side of her was larger than her right side, but it really wasn't a huge deal. You exaggerated the disproportion in your final drawing though when you trimmed her neck for some reason.
Also, the position of her upper body looks unnatural. Her head and neck are hunched over, but you've popped out her chest. It isn't an impossible position, but unless she's SUPER tense, which she's not (judging by her facial expression and overall posture), she probably wouldn't be standing so tightly. And again, when you trimmed her neck, it just made it look even more uncomfortable, kind of like she's actually trying to stick her head out as far as she can.
I would say to look at the anatomy of comic book female heroes, since you're going for that style. Maybe She-Hulk since you're going for that more beefed up tone. Don't get me wrong, it's super important to reference from life, but in this particular case, I feel like getting a reference that's a little more direct would help you a lot.
Ha, I hope this is more helpful to you than it is off-putting. I keep rereading this, and I feel like I'm being mean.