I'll venture a guess and say the reason her head appears so big is because it encompasses both hair and cranium. Really nice work, congratulations!
Two things to look out for : watch those triangles around the eyes and mouth. They'll come back to haunt you when you are creating morph targets(or however facial animation is done in HL2)
Also watch polygons around joints. You may see some popping in YourFavoriteBipedAnimationSoftware.