Hey! I like your line work, you have great sketches! try to fit a full-fledged figure into the format (I was often scolded for this during training). try experimenting with light and shade and volume. I love your work, keep it up! good luck with your studies.
This is actually quite expressive. Expressive is more important than strict dimesional accuracy. No one ever thought the Vitruvian Man was sexy.
That being said, if you find yourself wanting to sink into realism in art, then the I would recommend to study a drawing methodology that permits quick assesment of the figure from a dimensional standpoint. The man's leg for example is good, but would be great if proportional AND expressive. Loomis figure drawing might be a good anchoring spot for you.