I am just so excited you started a sketchbook here (seriously). It's so awesome when people come here so young and practice so hard. Please keep posting because this stuff is awesome.
The light source in bloody eyeball chick (love it) is sort of ambiguous. That's a complicated one though. As long as you keep doing studies in between imaginative work you're going to get it. You're on the right track.
At a very young age you have good start in your sketchbook all I have to say to you is work some more on life drawing and still life a little more and values your character designs also dont try to think too much while sketching try to go by instinct and have fun also if you are looking for inspiration check out other people sketchbooks for ideas and look up feng zhu tutorials on youtube that should help you