Hey! This is looking great so far!
I think something that'll really help you out, would be to try practising drawing motion, and lines of action, rather than structure. In university life drawing classes, we're often asked to do multiple versions of the same, or similar poses. One that focuses on structure, like you're doing here; lots of boxes and cylinders to represents the puzzle pieces that keep us together, and then poses that focus moreso on just the outer line of the body, paying attention to how the body curves, how fat and muscle hangs off of and affects the silhouette of our bodies. Look up examples of gestural life drawing, and try to imitate what they're doing.
Also, keep it lose! Don't press undo, just do single long, confident strokes, rather than hundreds of short sketchy ones (I'm still struggling to get out of this habit). If you happen to mess up, or you aren't happy with a line, don't stress over it, and don't erase it! Just keep going, and know that you'll do better next time. Allowing yourself to make mistakes and move on, rather than doing everything in your power to fix them, will help you improve a lot faster.
Best of luck, and keep up the good work!
