Great progress I've looked through the entire sketchbook. Really starting to shine. I think that for you to take the next step it's time for some long fully fleshed out pieces, meaning 10-12 hour imagination concepts/illustrations. You have the knowledge now PUSH for that beautiful finish that comes with hours and hours of work. The bright side is that after you to a few of those 10-12 hours ones youll be able to do it in 8 hrs, and so on.
Overall though, great everything.