Given there no actual photo of exactly what is being sold, I'd say you'd find it very hard to win any INAD case. I think the listing should have the typical combined size eg 40cm x 40cm or whatever it may be.

I would have no no idea how much fabric 100 grams would be in area.

Perhaps a photo with a typical selection of fabric witth a ruler in the photo would be beneficial.

The longer I sell the more I realise that the photos/description need to cover every aspect (essentially a disclaimer) of the item being sold.

By not being very specific in all areas you leave yourself open to buyer's, like the one you mention, to dispute.