Hi there. ~
So much work! I'm impressed how dedicated you are to this project! Wow...
I've a couple of thoughts though...
You say you're trying to emulate Sugimoris style but I think you might not be actually looking and what he draws and how he draws hard enough to really do it justice.
(Though I personally think developing your own style would be best, I understand what you're aiming for so I'll just crit there)
I'm not trying to offend you by saying that, so please don't feel hurt!
I think you might be using the baize tool, or something similar to create your lines? If you are, I think you should stop, and start actually drawing your lines. It may look worst at first but I can guarantee it'll make it better overall. Even if you're not using a tool like that... The problem with your lines at the moment is they are all gentle curves. There's no variation to create interest or give the mons a sense of form. It doesn't do your sense of proportion any justice at all, and that's never good :'(
I'd also like to say, try varying the line width (just look at sugimoris stuff for this) the line changes thickness and tapers off in various places, so it looks more natural and like what you're trying to achieve. That will help you alot, too.
I guess that would be it, for me. The volume of work you've produced is incredible, but I'd really like to see you take it to the next level.
All the best. :')