Hello and welcome to our User Group. I am very sorry you have had this recent news, which must be both a shock and very alarming. I feel your vet has done all the right things. Fluid therapy is the first line of treatment, in an attempt to flush out the toxins and get creatinine specifically more towards stable. Unfortunately, the success of fluids relies on the health of the kidney organs themselves. Once they are severely damaged, no amount of fluids will improve things beyond the level that is reached.
In addition, of course, there are the other complications you have mentioned. The anemia is a big one. The blood transfusion was the right approach in my opinion, but this is only a short-term measure. In normal circumstances, once the creatinine is brought down, a vet can concentrate on other issues (such as the anemia), and attempt to stabilize them one by one or collectively.
Sadly, I believe the kidneys may be just too damaged to improve the prognosis, which means it is unlikely any intervention will really improve things from here onwards. To obtain a real idea of how things are, your dog would need an ultrasound scan. This would detail how much kidney organ tissue remains and whether there is any chance at all of any improvement (with diet changes, medications and good management - and assuming the other issues could be resolved). However, the decision is difficult, because you may not want your dog to be prodded and poked around even more. I don't envy your situation or this decision, but I do empathize greatly.
The SubQswill help your dog, so I would continue doing them. They will help make her feel more comfortable, but only for a short time. You could also consider undertaking more IVs, but do you want to risk her passing while not at home? Probably not.
I wish I could say something that would be helpful. Sadly, I do get the impression that the kidneys are just too far compromised - and further rapid deterioration is likely. I cannot and will not even attempt to advise what you should do. But I am here to offer support and information, should you need it, and I'm happy to try and answer any further questions you may have.
It's the hardest of things we do for our beloved pets ... allowing them to leave us when the time is right. I have been there too many times in my life - and each time is as hard as the first time. But, we do it for all the right reasons, and certainly not for ourselves.
Just try to enjoy what time you have.
Give her whatever she wants, when she wants it. You cannot do anymore.
Thinking about you.