Tiger, of sorts

I don't think that you failed to portray the expression at all! I think this is mostly a case of not ''exaggerating'' the expression enough. The main things I noticed and added were the wrinkles on the muzzle; when drawing them, think of them as sort of ''tubes'' of muscles placed on the nose of the animal. I also curled his upper lip a bit more. I also think that in this case, not drawing the whiskers hurt the expression. On the ref you can see them standing way straighter up than on a relaxed tiger, so this helps the viewer to see how the muzzle curls during the snarl. Another thing with animal that helps translate their expression are their ears, so I've pushed them down even more and slightly rotated them towards the inside As for the fur texture, I think that you've pretty much got the technique down; the way you've added the texture on the transition of color and on the outside of the form is pretty much all you need to suggest texture. Now it's just a question of rendering until you're happy with the result! One thing more thing I'd suggest about the rendering and texture is being careful to not overuse the smudge tool. Fur often creates hard lines, and you've used such good and vivid colors that it would be sad to see them muddied. I hope this was helpful!

you could add some creases as shown