get your hands on some Baby beehinds bamboo fleece fitted and some decent covers hon.
I personally think bamboo is more absorbent for heavy wetters then hemp and id be interested to know what kind of fleece is being used on the nappies andhow many layers? Id also be interested to know how many layers of hemp your nappies have and how many the boosters have.

you can use fleece covers over fitted successfully for heavy wetters as long as there is enough absorbency in the nappy itself.