30 minute sketch

I think what would help loads is allowing yourself to become a lot more fluid with the way you sketch and allowing yourself to follow the curves of the body instead of sticking to the structural guidelines you provided for yourself. Sounds counterintuitive but knowing that the body very rarely has stiff lines and follows both convex and concave curves helps more when drawing gestures. Starting with the spine helps me define these curves the most.

This is Great Scott! Love that you added some value in this drawing. Don't be afraid to make a more detailed under drawing so that you can really nail the proportions. One thing I like to do is do a couple of quick gestural thumbnails of my reference before I hop into the a longer piece. It give me more confidence when I am approaching the figure.