At first I thought that was a tree in the background and not her antlers. With where you've placed the lights, and the distance they shine, there's no reason for the part of her head where they connect, not to be illuminated.
What I recommend you do, is making a couple of studies, with a very defined light source. Find something that forces you to work with hard edges.
I love that you've tried doing something really difficult here though. It shows that your not afraid to get out of your comfort zone, which really is the most important thing. Keep up the good work!