Confidence is funny like that. I missed the first deer I ever tock a shoot at. It was a Doe at 35 yards. I watched her for 20 min befor she gave me a shoot, by the time she did I was so wired up that I couldnt keep the gun steady. I missed her at 35yds, looked for 3 days with out a trace of hair or blood, clean miss (with a gun). That year I passed on a spike that I wanted to take but my confidence was not there. The next bow season I passed up another spike with my compound, that same fall a big 9pt came in to 70 yards, head on, and I droped him were he stud. Since then my confidence has been un shakable.
Confidence can be lost in a matter of seconds but takes for ever to come back. I would say get as good as you can be and get out in the woods. If it feels right shoot if not pass on that deer, and remember some day it will come back.
Good luck and dont let it get ya down, we all faulter now and then from perfection

. Get back out there.
KILL