I’m so sorry. This is so tough. She’s a beauty ❤ I’ve done the sub-Q fluids for three kitties. It works very well. It does take getting used to but once the routine is set, it can be smooth. It really does extend their time, sometimes for years. If the IV flow is too difficult, you can use giant syringes instead. Do you know about Epakitin? It does wonders. It’s a powdered supplement that you can either sprinkle on food (that never worked for me) or mix into a small bit of milk (that worked). It binds to the phosphates in the food and reduces the impact on the kidneys. It works really well — I highly recommend it. You get can it online yourself or sometimes your vet can order it for you.
Good luck Classical Sass — sending love and hugs to you both.
Here’s the Epakitin on Amazon: