No, I mean... the back of her head looks very small, when you take into account the size of her face.
Heck, it could just be my love of large-headed figures. I don't mean to trample on your art or anything like that. I just noticed it because I have a friend who does not give her drawings brains! The back of the head is always flat. XD
On this gal, its a 3-quarter view, so you're not gonna see the back of head as you would, let's say, the side of the head. You see the face more because the head is basically turned so you can see the face more. The size of the face doesn't always equal how much of the head you see because it looks different at certain angles (like in a front view, you see none of the head at all, just the face and the crown).
Also, you have to take account that not everyone has a cut-dry single one head shape. Some people's heads are flatter in the back, some protrude out further and are more spherical in shape. The head sizes and shapes vary just as much.
Oh, I know. I draw 3/4 views a lot. And I also know that all heads are different. I just don't think I've ever seen a head like this one. I guess I just think the face is turned at a slightly different angle than the head itself...? It might be the eye hiding behind the hair that is throwing me off. Perhaps the size of the neck. Or the breasts. XD Maybe a combination of things. But something does seem off to me, no matter how I look at it.
HOWEVER. I do like this piece. Especially the texturing on the hair and shorts. :3