how do you wash them?

a strip wash will only be a temp. fix, if your usual washing practice, is not how you wash MCN.

not saying you do this, but it's worth thinking about, JIC you do wash with too much washing powder, use fabric conditioner etc. (I have no idea of how you wash your LO's MCN's.

tablespoon of MILD washing powder (e.g Planet Ark Sensitive or Ecostore) in the pre-wash drawer
same in the wash drawer
no fabric conditioner
no napisan

what do you mean about "nappies from kmart"? i have seen synthetic covers there and very low absorbency fitteds - but that was a few years ago.

is the absorbency in the baby beehinds, bamboo, microfibre etc???
bamboo is the most absorbent fabric in MCN materials
baby beehinds used to have "baby beehind foldups" - great for boosting the absorbency of nappies.

for a heavy wetter, i would avoid all in ones, as they are harder to boost.
i would go for all in twos and pockets, much easier to customise the boosting, to suit YOUR child.

If you buy pockets that come with free microfibre boosters, i would suggest you buy bamboo prefolds, trifolds, etc, to stuff the pocket with.

Fluffybubs AI2 for example, come with snap in prefold, snap in boosters.
WhizzKidz AI2 for example, come with snap in boosters.
both are bamboo for the absorbency part.

Fit is very important.
If you get leaks at the legs, it's a fit issue.
If you get leaks at the back, that nappy might be not a high enough rise for your child.
There are front and side closing nappies. If i got the nappy fitting nicely at the legs for my LO, then the waist would not fit, and vice versa - this was our experience with front closing nappies. As soon as i put her into SIDE closing nappies, the issue disappeared, as you can adjust them independently.

the other fit issue we struggled with initially, was the crotch width of nappies.
many OSFA styles, were very wide in the crotch, and my DD, whether a nb or a two year old, suited NARROW crotch nappies - which are usually found in SIZED nappies (not osfa).

Your child is two, the question about WHEN to stop buying MCN is impossible to answer.

Are you planning to have any more kidlets? If you are, even if she toilet trains this summer, you would have those nappies for the next LO.

Some kids toilet train at 3, 4, 5.

So very hard thing to give you an answer on.

so , a few things to consider. One or none of them may apply to your situation, but i have given it my best shot - considering i know nothing about your DD and her nappies, ha ha.