I've never used Itti Bitti on DD. but I have had a lot of fitting issues which I've worked through with some help from a nappy store.

If there are gaps, u need to pad it up. -But if u pad it up with only the bamboo (high absorbency stuff) it actually stays really wet on LO's skin and/or doesn't absorb fast enuf.
-if you pad with only microfibres, which takes less amt. it can only take however much before its saturated. Then it behaves like a sponge (squeeze, out comes weee.....)
So my solution had been to makeup a combo. Microfibre closer to DD's skin & bamboo the next level. U can pad up a few microfibres to make the 'gap'.
Hope this makes sense. :-)