You've really made some great progress so far! Some tips I would give for your further growth are the following:
1. Learn some basic anatomy and try to exaggerate the muscle structures to emphasize flow and movement in your human figures.
2. use a combination of straight lines and curved lines to introduce contrast in your figures and make them feel more dynamic.
Finally, here are some books I'd recommend for gesture drawing:
1. FORCE: Dynamic Life Drawing, by Michael D. Mattesi
2. FORCE: Drawing Human Anatomy, by Michael D. Mattesi
3. Constructive Anatomy, by George B. Bridgeman
