Really great progress dude! Uhm the only thing I can say, is these drawing manuals, they are great, but don't be afraid to break away and do studies that you regiment, and make sure you draw from your head as well, you don't want to fall into the trap of being a human photocopier.
Good advice; thank you. I'll seriously consider this, as I do very little from imagination. BTW, your sketchbook certainly demonstrates the value of hard work and focused study! Awesome stuff!