I honestly don't know where to start.....
My advice would be to get really good at tracking, because if you continue to take shots like this one, I'm betting that your going to be doing a lot of it....

The first thing I would do is think of where all the white hair on a deer is. With white hair on the ground then that's where your arrow cut.
For what it's worth, white hair is not the best of sign to begin with, and particularly not with you being on ground level with the deer.