Does your baby have chubby thighs/tummy? Long/short?
My DS was avg/short length with slim thighs (for a baby) and the bumgenious and green kids pockets worked well for him, as well as some homemade pocket nappies that also have quite wide crotches.
DD fits the ittibitti d'lish quite well adn I've made her some narrower crotch nappies - she has chubby thighs. She's long for her age though, and also big around the waist so the mediums are already quite tight on her.

Do you have a sewing machine? You could make your own inserts/booster pretty easily. There are sites taht sell all the materials you nned.