It's not thrush btw.
She is BF, and her tongue looks normal on the outsides, but the middle bit of her tongue looks very smooth, a little pinker than the rest, and no little tastes bud spots poking up like the outside. its the whole central bit, starting about a few cms from the pointy tip, in a patch as far as the eye can see to the back.
We wondered if its where she sucks hard on the boob?