I don't even really remember being potty trained, pretty much proof that it was too early.
...
For some reason I'm dying to tell this story again.
When I was three or four (I don't remember exactly) I spent a large portion of my days at a babysitter's place. Everyday around noon or so, the babysitter put her own infant daughter to sleep, and took a nap herself. During this time I was instructed to make no noise at all, so as not to wake the baby. About this same time each day, I would almost invariably need to pee. Of course, being autistic, I can get pretty literal sometimes, and I thought that getting up to go to the bathroom would make too much noise, so I wouldn't go. Which frequently resulted in me wetting myself all over her couch. As punishment, she made me wear a diaper and stand in the corner. And she said to me "If you pee in that one, I'll just change you into another one." I never did it.

I got bribed with disney land/world to get potty trained, had a few accidents, but nothing serious.

I wet the bed a whole bunch when I was real little, probably because I was potty trained too early. I never got in trouble for it, though. I wet the bed a couple of times because of dreams, but that's it. Of course, daytime wetting was a different story. I remember having accidents several times because I was afraid to go to the bathroom. Actually, that was what happened during that accidental abuse episode.

I used to wet the bed, but it was mostly from stress. Now I just get sick when I'm stressed.

Well it didn't really seem like something that would be traumatic, but here I am with this fetish, and I can't think of any other reason why it might have happened.
Personally, I like to mess my diapers, but I always make sure it's gonna be easy to clean up before I do it. And I shower afterwords.
I also have a bladder and bowels of steel, so I can't wet or mess myself except completely deliberately.

Don't like the sound of that, the accidental abuse part that is. I mostly got into diapers because I found them comfortable. After that, I figured, why leave them to waste, and started using them. Hate messes with a passion though, so I try avoiding that.

I suppose some aspects of my infantilism come from that support pillar you were talking about, while the diaper fetish parts come from the accidental abuse I received as a child. Over the years they've just sort of bled together.

I don't get a sexual charge from it at all to be honest, but I can understand how it can be sexual, written a few scenes in my stories.

Well, I get comfort from it, too, but the sexual part tends to get in the way. Although, I can suck my thumb (and I never stopped from when I was a baby) without becoming aroused.

I find infantilism comforting, not a sexual charge personally.