I think you are too afraid to use hard lines. Its okay that not everything is shading or lightly drawn. In situations where you have a white background or need to differentiate 2 solid object, use a harder outline. Everything right now fades together. I'll post some of my non-nolan related stuff later if you want to show you what I mean.
Below is a pencil drawing I did of Will Smith from one of my favorite scenes in I, Robot.
See how most of his face is shading but at certain parts, his eyelids, his nose, his shirt, his lips, etc. I used a hard line. I know your thinking that outlines are bad but they exist in real life. They differentiate. So don't be afraid to darken things up and really distinguish. I think once you really find out how to do that after some experimenting, you'll be pretty darn good.