I've made a few changes in pink - the brow line for the boy you might have already connected.

Technically, 3/4 view is the hardest to do - as do most people, you put a little too much on the "1/4" side, so the face looks distended somewhat. I remember this lecture clearly from sophmore year at Mass Art (Illustration major). Most people actually screw up the mouth in the 3/4 view with people, because we SOOOO want to draw a whole mouth, when a lot of it is indeed hidden.

Oh, and her necklace would fall a little further down, that's a minor point.

Does this help at all?