Couple of things...

• As has been said: The forearm, hand, and any parts of the fingers before the string should be completely in line with the force they are exerting. It takes a lot of muscle to bend a hand while supported something very heavy (I used to bowl a lot) - and in this case (different to bowling) there would be no advantage in doing so.

• Lighting: Very dramatic but, unfortunately, not very realistic. Even after all the blurring, the "forest" behind her is being lit from behind, somewhere from the top left corner. The young lady however is being lit, very strongly from right upper front, and the parts facing the forest light are in deep shadow.  Just doesn't fit in.
  I'm sure the you want to keep the light on our young heroine - so maybe you could darken the background. Also, as she seems to be in the middle of a forest then you could consider giving the light a shade of green.

Besides that - nice work!

Rô

My favourite question is "Why?", my second favourite is "Why not?"