Well, I'd say don't beat yourself up too much. A guy I read about who got into gunsmithing and building guns started out as a jeweler and watch maker/repairman. He started fixing guns on the side for friends; later on he found that he was actually making as much and more doing gunsmithing. He made a career change (said that after working on tiny watch parts that gun parts were positively HUGE in comparison) and never looked back. To the best of my knowledge, he never got "formal" training in gunsmithing; just used his skill and aptitude--with a good deal of common sense mixed in--to make a thriving business out of his work with firearms.
The guy's name is Bill Wilson (Sound familiar?
If your passion lies in the maintenance, repair and building of firearms, go for it! Best of luck to you.