My rescued cat has IBD ;( Help!

I love my cat, China Cat. She is precious. My daughter rescued her from a non kill shelter. We were told she was young. After getting her home, she was having diarrhea out of the litter box. We thought it was from stress of being in a new place.  Then, she started peeing on our carpet. We took her to the vet and did a poop test. No parasites, everything normal on that test. The doctor gave us anti diarrhea medicine. Didn't help at all. I tried pumpkin, no help. We switched her foods gradually to several prescription ones for sensitive stomachs. No help. Now she is on no grain Blue buffalo. Still no help. She poops and pees on our couch and drips on my floor. It really is disgusting. She has lots of gas when she poops. Sorry to be so descriptive. Funny thing is, it doesn't seem to hurt her. She is still active and very loving. She is the most loving cat. She loves to snuggle and be near me and even follows me around my home.

Apparently, before we got her she was abused. She has been stabbed previously. She only has one tooth, a fang at the top, and some little tiny ones on the bottom.

I am cleaning up diarrhea almost daily. The vet said she has IBD. The vet also said it is possible she has a kidney disease. He said her kidney seems small.

My vet didn't do any blood work. He told us to go to another vet that has an internal specialist. I can't afford it right now though. Ugh!

I'm going to look into pet insurance.

Any help please?

When my cat had loose stool, what worked was acidophilus and Nature's Variety Instinct Limited Ingredient Diet canned food. I believe Blue Buffalo has carrageenan and it made my cat vomit. I have a large crate to keep him in when he's not doing well or nervous. He actually likes it and seems to calm down in there. 

My cats symptoms aren't as severe as yours, but I've been treating this for months which the vet told me was to be expected.  It's been two steps forward, one step back, \- he seems to feel just fine with the exception of the loose stool.  At least he's back to laying some cable now.

Here's been the regimen thus far:

1.  Purina EN wet cat food (I got it online at Chewy, pricey, but...)

2.  Probiotics - I was using the Purina one for cats, but people on here have recommended others which I haven't tried yet

3.  Metronidazole - I have this compounded, we're on the third bottle, but it has helped and I don't have to pill him!

4.  Prednisalone (spelling) - This is compounded also, I just got the scrip for it and so I can't tell you if it worked yet.

I might try some of the freeze dried raw food, but I don't want to try the medicine in combination with other things yet. 

At first I was panicing because it wasn't clearing up, but apparently this is a marathon not a sprint.  The vet said if it gets worse he'll test him for pancreatitis, and if it doesn't then I have to be aware that it's a chronic condition that will flare up.

Unfortunately the problem with pet insurance is they won't cover pre-existing conditions.  That said, if you do have other pets, it's really worth getting it early - I have a high deductible policy that's very affordable. 

Poor China Cat. And poor you. I know how frustrating it is to have a cat with diarrhea, especially a long-haired cat. Did China Cat have diarrhea at the shelter?