I know the feeling. Shortly after I got married I decided to tell my wife, she was the first person I've ever told. and man, did she ever flip out. For a while, she thought I was a pedophile, and insisted on seeing a shrink. So we did, and the guy convinced her that there's nothing wrong with me and although this is one of the more unusual fetishes, its not unheard of, and it's definitely not sick or dangerous. The best argument he used was that if I was a pedophile, I'd have hurt a child or been caught with kiddie porn or something by now, and that I had no signs of that.
I agree with the arguments that this camp is a bad idea. Also, I'm not so sure about the "Christian shrink". Nothing against Christianity....I gave up on it long ago for a variety of reasons (none of them diaper or sex related) but I worry that a Christian shrink will side with your mom. The thing is, hardcore Christians and Puritan types, while generally nice and well-meaning, tend to be slightly out of touch with how the real world works. I'd say a professional psychiatrist is the best bet to clear the air with your mom.....he won't take sides and will be able to supply concrete explanations for your interest.