It's really coming along nice
Judeging from the references (like I said, I've never seen the character before) your doing a very good job!
The only thing I could mention at this point is that the part of the cheekbones that goes towards the ears could be a bit smoother and thicker (from up to down) and maybe the jaw could be a bit bigger.
There's a very fast image that I tweaked so you could compare with the image you up loaded. Hope it helps.
I like how it's developing
Take care buddy
What?!! No hat!