have you tried using a microfibre insert on top of the bamboo and hemp? I have found, that if I don't use a microfibre one, he pees too quickly and the bamboo doesn't have the chance to absorb it all. Whereas, microfibre is faster to absorb the liquid, and then it seeps into the bamboo slower. Never get leaks that way.

Oh - and I always give hemp and bamboo a good 7 washes before expecting them to be at their full absorbency - but that could just be me!

HTH!