But you should note that I haven't DDSopted anything besides HRDLC. I'm pretty sure the major culprits for me are Interesting NPCs and Detailed Cities, though I haven't spent much time determining memory usage of each since it sounds like a huge pain.
That's alot of mods, but I think I have more. Honestly I don't think textures are your problem. As you can see my VRAM usage is more than yours, but my RAM usage is considerably lower... over 1GB lower. That's huge. Personally, I would start with a fresh vanilla Skyrim and install mods a little at a time and monitor RAM usage to find out which ones add the most. I recently went through my list and got rid of the ones that I figured I could live without in an attempt to make my game stable with uGrids=7. Unfortunately that proved futile. The engine just can't handle it.
I find my VRAM usage to be insane as well even using only 2048 textures and pretty routinely get close to 3gb usage... this is an issue I'm struggling with myself.
I've only DDSOpted the big TeX packs though so we'll see as I go along.
I routinely go over 3GB VRAM usage as well, but as long as physical usage stays below ~2.5GB I'd say you're golden.