Critique on structure and proportion

hhey first time posting!
Drawing only female read models with pen and paper, 7 poses for 2 min and 3 more poses with as much time as i need.
The goal of this practice was accuracy of orientation of the major masses of the body and proportion. I had difficulties with n°9 because of the sideview and overlapping of shape (with the pelvis, the bent leg and arm). I’d like to find a better way to draw joints for limbs cuz it can get a bit convoluted especially when bent.
Feel free to critique, and suggest ways of drawing joints.

https://drive.google.com/file/d/1rO0mXvksthqO-yfZ3brk-bIyl_9C3F3X/view?usp=sharing
https://drive.google.com/file/d/1SbwGsW6-66WBAL6zr45lQ5wiqoehnabv/view?usp=sharing

The use of 3D shapes (cylinders, cubes, spheres) is great and you have utilised them well. 

Have a go at using more natural shapes (still make them 3D) instead of the boxes for the pelvis and rib cage. If you do this, (rounding the edges slightly etc) you will find it closes to the anatomy and will find it easier to adapt the poses and build a drawing from them.