Your thumbnails are good. You've got your playlists sorted as well. It also looks like you're sharing your stuff on Twitter, Facebook, Google+ etc...
Your videos are edited well with music added, and your personality shows throughout your videos. You've pretty much got everything I could give advice about down.
I see no reason you wouldn't start growing like crazy real soon, as long as you stay consistent. You've definitely got something going, here.
Also, you might want to try posting your stuff on Reddit if you don't already. Maybe try some of the more obscure sites, like Digg, or others I can't think of right now. It honestly seems to me that your main problem's lack of exposure.