Very Nice!. If you want to get all CSI on it there is some good reference material here
Some movies of facial muscles working too if you ever plan to animate it.
I did a quick photoshop overlay of a female skull and your model looks pretty good. I would change front crown to leave some room for scalp thickness. Maybe a little too projected in middle of the face and just slightly under protruded in the chin. Bit too much space at back of head.