Okay good!
So unfortunately ditra and tile will not make up that much
I assume you are installing a porcelain tile that will be at most 3/8″
So with ditra and thinset you’ll get another 1/4″
And overall height would be about 5/8″
My suggestion would be to install 1/4″ backer board, then ditra and tile
Not much else you can do with that much of a gap
Hopefully you can afford the additional height and not make the transition to your other flooring too high or awkward
