Hiya,

I had EXACTLY the same problem.
this sounds silly but be really careful when you put them on and check that they are really tight in the crutch area.... after i put MJ's on now i get her to stand and pull them up higher and check that there is no gap.
This has seemed to work fro us.
the other thing that is fantastic is a wool soaker - will wick instead of leaking.
I feel your pain!!!

HTH