What am I doing wrong?

[Arimeh]

What sized covers are you using over them? If the covers aren't big enough the moisture will wick into other materials near the nappy.

Other than that.... I would just make it tighter - I make mine so it doesn't have any holes near the tummy.. if that makes sense?

[1MOREPLZ]

have to agree with Mel here....
i make them tight enough round the belly that there are no gaps..if you get what i mean...
Jack can snuggly fit into a small cover BUT i use a medium so it isn't cutting his belly in half....

[Ezz]

I use a large cover on DS, to give plenty of coverage. I find sometimes the top of the nappy will creep out the top of the cover if I use a medium - and that would cause a leak!

[Nelle]

1. Has someone accidentally tucked her top into her nappy?
2. As the others mentioned, check the cover size to make sure no nappy is poking out.
3. Is it the front bottom of her tshirt, with a front closing cover? And is she a tummy sleeper? If she's a tummy sleeper, you might want to try some side closing covers (Motherease Airflow for us). The cover won't dip down at the front because it does up at the side. That stopped leaks for us.