What would be the minimum size for a galaxy to have a disk form?

[Adraasa Kynuei]

So looking at pictures of dwarf galaxies and how they're just an irregular (pun intended) mess and they do not have the disk shape that we, ironically, associate with galaxies despite a small minority of galaxies being big enough to have and maintain their disk shape.

Like apparently the Magellanic Clouds were once spirals but got screwed by gravity from Milky Way but the little bit larger Trianqulum has managed to stay intact despite being in the presence of the more massive Andromeda galaxy.

 

[secur]

I suppose you've looked at https://en.wikipedia.org/wiki/Dwarf_spiral_galaxy? Says diameter can be less than 16 LY (much smaller than Triangulum at 60LY). One problem: they're hard to see far away, so we don't have a large population to study. The other problem, cosmological dynamics aren't understood well enough. Hopefully someone can give a reference to research on the topic, but don't expect a definitive answer.