These days, I suppose I'd call myself a "diaper sissy," in that my diaper preferences are girly when possible and neutral otherwise. That started when I was 12 or 13 years old and finally got up the courage to hike to the store with my allowance and buy Pampers. For years, I'd been playing with the old cloth baby diapers that were still around the house, but the disposable diaper ads on TV were too much. I had to get some. This was 1989 or 1990, and baby diapers came in girl and boy versions. I bought the girl ones, initially because I wanted to make it clear to the store employees that I wasn't buying them for myself. Talk about goofy!
But, I was a kid, and those kinds of countermeasures seemed important.
It turned out, though, that wearing the girl diapers made me feel especially naughty and little, so I kept buying them--and, fortunately, was never caught! (
Unfortunately, the gender-specific Pampers and Huggies were only around for a few years.
)
Later, in my mid-teens, I went through a phase similar to what others have described: I borrowed bras and panties and other articles of female clothing from both my mom and my sister, and played with dressing as a girl. It never left my bedroom, but it went on for several years and was almost as captivating as the diaper thing. It wasn't until my late teens that, very suddenly, my interest in wearing girls' things disappeared, and was replaced with an interest in see girls' things on girls.
By that time, there were no girl/boy diapers, so my sissy was fully backburnered.
(I could relate some humorous anecdotes about digging around for things that would be good to stuff bras with. Tissue paper was never satisfying. But, I digress.)
Over the last eight years, since joining ADISC, I've gotten back into wearing cloth diapers, and though most of these are prefolds and thus gender-neutral, I've indulged my trace remaining sissy-ness with some cloth training pants in girly prints, and (recently) some My Little Pony cloth diapers and diaper covers. Love 'em. (I don't count myself a "brony," by the way. I just find the MLP stuff cute. {{blush}})