the few dark pixels you have around the edge of the hair still makes it look flat - it's not because it's not shaded well, but because it takes contrast too far - when you compare the value range of the hair on the head to the edge, err. How do I explain it.
Because edge of hair is so dark, it makes the rest of the hair look flat - it tricks the eyes to not see the shading and highlights of the rest of the hair because the brain averages stuff and blah blah.
Smooth that stuff up anyways, there's not reason for the edge of the hair to be so contrasty. You haven't painted that kind of 'outline' on, say, the bottom of the chin, so there's really no need to apply that tech to the hair either.
Except for that, though, hot texture you've got going on. You're good at this.
