That was quite a question to land on you suddenly like that! I can see why you said no. I think I would have too, or at least said 'not so much' or 'not really'. Then, when it's too late to change your answer, you're left thinking about whether you said the right thing.
It might be best to drop it as mm3 suggests, if you see no benefit in trying to get your Mum to understand. Or it may be worth continuing to help her understand. Only you know the situation well enough to decide that, but I'd thought I'd offer a few suggestions that you can use or ignore as you think best...
I wondered if you could bring the subject up with your Mum by asking her what made her remember when you 'used to' have that thing with diapers, and then talk about it all in the past tense. Maybe, when you were younger, your Mum was frightened about who or what you might become, especially as she doesn't seem to understand DL or recreational diaper wearing. Would she ease up a bit if she was speaking about the past?
But that doesn't solve the problem of her knowing now. I dislike deception, but I also believe in not telling people what they don't need to know.
So, I told my Mum that I like to wear diapers at night sometimes. This is true. I also like to wear in the day sometimes but she didn't need to know that and I think it was enough for her to get her head around that first bit of info.
You are not unusual (I think) for getting a sense of security or emotional energy from wearing, rather than it being a sexual thing. For me it's pretty much 95% non-sexual with a small amount of cross-over. So I told my Mum it helps me cope with stress and I don't get off on it.
I also tend to emphasise that my interest is in my own childhood and the special time it was. I hope that goes some way to show it is not an interest in children, but with the child I once was. Also, if your childhood wasn't awesome, be careful how you say things because, at least in my experience, parents tend to blame themselves for anything about their kids they don't like. Parents may be less amenable if they are also battling feelings of guilt, wondering what they did to cause something.
Anyway, that's what I can offer from my own experience. Your situation will be entirely different of course so do as you know best. Let us know, in time, how things turn out.
