Buck fever hits us all at one time or another. The thing I have found to combat it is to focus only on the shot. Once you have determined that this deer is the one you are going to take focus only on what is happening in front of you. Think about where he is going to be when he steps into shooting range. When he does step into a shooting lane, focus on exactly where you want your shot to be placed. It may sound silly, but in my head I keep telling myself what Mel Gibbson tells his sons in the Patriot, "aim small, miss small".

I think what messes some people up is that they start to think about all the possibilities and what will happen after the shot. This can really get your mind unfocused on the shot. Another thing I have found to help is target practicing with deer targets. Shooting at a round target does not help you pick the exact spot you want to hit on the deer.

It sounds like you are doing the right things, more experience in the woods will help you out a lot.