Shooting fawns is risky business. My first deer kill was a nubbin fawn. I may have only been 14 at the time, but I've never shot a fawn since then.
My take on killing fawns is, unless you have to earn a buck tag, just let it go. You may be killing tomorrow's buck, and it's almost never worth the risk taking the kill. It's the only time I've felt bad about killing anything in my hunting career.