I feel your pain
I've been deer hunting for 25 years now. Probably killed 70-80 deer. And yes, I've wounded some and never found them. It does feel horrible, but time will ease the pain. And like you've said, you have LEARNED a lot. This is the most important thing, learning lessons forom this experience. Like when to take or not take a shot or whatever.
I've been bow hunting for about 15 years and I don't know anyone that's been bow hunting a few years that hasn't lost deer. I actually trained a black lab to track about 5 yaers ago and it's amazing what a well trained dog can do. This may sound sick, but I got a lot of enjoyment just watching the dog work. Sadly, he was stolen 3 years ago right before duck season.
Also, I have seen 3 legged deer on 4 separate occasions in my hunting years, soi know they do live a lot of the times on leg hits. Usually a leg hit will bleed small droplets of blood and if the deer is allowed to lay up or even stand still long enough, the wound can coagulate and stop bleeding. The only leg hit deer my hunting friends or I have ever found were ones we were able to keep moving. This goes against common advice of letting a deer lay up and die, but the only way I know of to get a leg hit deer is to keep it moving. This is where a good dog is awesome. We found one after tracking it 2 miles with my lab one time. Some bigger dogs will actually run a leg hit deer down and catch it.
I also agree with looking for a reasonable amount of time. Reasonable to me is if the meat is still going to be good.
And always remember God put coyotes and buzzards here for a reason.