I stuff all my pocket dipes with a large hemparoo. I am way to cheep to buy small, medium and large hemparoos, so all I have are larges. I used them in my small dipes with no probem, just folded it a bit, they fit great in the mediums, and I assume they will fit in the larges just fine to when she grows into them.
I found prefolds to be too bulky, so if you are having that same problem, you may try the hemparros, but just buy the one size!!!