If this is your first year bow hunting you're learning that shooting at a live deer is quite a bit diffrent then shooting at a target of even a 3-d deer. Filedmouse hit it on the head. Jitters will get you and even sometimes it's not jitters. I shanked a shot on a doe earlier this fall. luckily I was able to recover her but I know better in my 12th season. It happens.

If you don't own a 3-d deer you might want to invest in one. I found starting out that this helped me alot and gave me the confidence to make the shot.