My friend, you have done a lot of work and you have improved because of it. It appears that you have improved your sense of proportion, nicely done. Keep working hard at what you are doing. Continue looking into the creative sides of drawing. However, as time goes by you may want to consider learning some perspective. There are many applications of perspective, essentially you gain intuition by keeping in mind the horizon line(eye level). In some of your drawings the feet are poorly placed. Knowledge of perspective will tell you that more or less of the top of the foot will show depending on the horizon line. For perspective study I recommend Perspective Made Easy by Ernest Norling. Good luck!