I've established a new Nether Portal established in Jungle Cove (its just outside the outpost on the surface) and I have found one, maybe two nether fortresses in the nether near it. I'll post the other pics in a new post.
It'll look better once the vines have completely grown.
Just to note, I'm using far view and have fog off. When I got to the nether, I soon noticed two objects of interest. The first one is the second image, this is to the southeast (the focus number in F3 works as normal) and while I initially thought this was a nether fortress, but I'm not so sure.
The second one, which is to the west, is definetly a nether fortress, right at the edge of far view.
Anyways, when I went in, there were pretty much just a few tribes of zombie pigmen, but I didn't stay very long (or explore very far) since I ducked out when I saw a ghast spawn.