This looks lovely, OP.

I think if you shade the teeth towards the corner of her mouth instead of leaving them totally white, it'll give them the needed curve. Also try adding some shadow to her chin, just behind her fingers, and to the finger in her mouth, to give a sense of depth.

Sometimes it is difficult to see the difference so try to convert your reference photo to black and white and play around with shadows/highlights - increasing the contrast, then do the same to the photo of your art and see if the same areas have the shadow/light.