Nice job on your younger pose, Julialiberali. That looks and feels like there's a lot of energy going on there.
I love how much of the C and S curves going on there, but I just cannot get enough of them in any of those attitudes. Would you please check out our interative online drawing tutorial on our website?
The reason why you could do this tutorial, is as long as you'd do this tutorial, you'd be able to start with quicker sketches that help you visualize the broadest strokes with the fewest amount of lines, then you'd end with the longest possible pose.
Cheers, and my hat's off to you.