Seriously. They are all gigantic. Well, except for the T'varo/T'liss. Is that intentional?
The D'Deridex is supposed to be big, I get that, but it's also designed in such a way to show that, while it may have a great deal of volume, mass-wise, it's not much bigger than a Galaxy. The model scaling for this one's probably fine.
The Mogai feels like it's probably too big, being wider than the Scimitar model.
The Dahlen is enormous, being the size of a Klingon or Federation heavy cruiser.
The Ha'pex, Ha'nom, and Ha'feh are ridiculous. They easily mass twice their federation and klingon counterparts and are far more substantial than the D'Deridex. Fly one next to a Lunc class or a Galaxy and you will dwarf them. I'm not just talking about the wings, I'm talking about the enormous brick of a central hull these ships have.