Sorry you're having to deal with having incontinence at an early age.
You might be able to wear some boxers or other briefs over the diaper to muffle the sound of the diaper.
But to be honest with you most people won't even hear the crinkle sound of the diaper in public because most public places are loud and nobody really pays attention to what someone is wearing under their pants.
The cloth like diapers would likely not crinkle if you're worried about people hearing the diaper.
And if someone does notice the sound and knows it's a diaper they will likely not say anything.