Good evening, Roxana, this is Polyvios. How are you? Awesome job on your forces, your forms, and your relationships, and tones. Keep up the good work.
But, however, I feel that the image would be perfectly readable if that image is in landscape mode. I'm also not getting enough of the caricatured forces and gestures in your body and head constructions. Would you care to loosen up your dominant arm with a 10-minute pose warm-up? Plus, check out Drawabox.con for some simpler drawing exercises and workouts. So that your lines, graphic shapes, spaces, and forms would be more controlled but intuitive to boot. And while you're at it, I'd suggest you'll look into the Force series of books/ebooks to rent or add to your collection. Good night.
Great line of action and proportions! Next time, maybe focus on developing the shapes/details (such as fingers, toes, etc.) of the figure before moving forward with the shading. Otherwise, a great study!