Asking for advice about my 13 y/o cat with IBD and chronic pancreatitis

I have a cat who I adopted when she was 7. I've had her for 6 years, so she's 13 now. She has always had problems with going to the bathroom outside the litter box, and this got progressively worse over 4 years. She started having very soft liquidy stools over the last 3-4 years.

I finally got her an ultrasound about 2 years ago, which is when we discovered she had scarred intestines indicative of inflammatory bowel disease and chronic pancreatitis. She's been on prescription wet food (Royal Canin dry/wet venison and duck) and if it ever helped, it was only a short time before she started having non-solid stools again. Recently she started going on furniture, all over the floor, anywhere was fair game for her.

Over the last two years she has lost 5 pounds (she used to be overweight at 12 lb, and now is just over 7 lb). I moved from Chicago to Rhode Island and that stressed her out a lot. I can't leave her overnight without her leaving a mess of poop everywhere and meowing incessantly after I get back, she is constantly meowing (overnight I wake up to it every night) and when I give her affection she doesn't seem to want it, only wants me to feed her. Lately she has been ravenously hungry all the time even after eating, constantly begging for food. She will eat all her food at once, and then vomit up undigested food several hours later. It's as if her intestines stopped working and the food just sat there in her stomach for hours. This vomiting started about 2-3 weeks ago, a couple weeks after putting her on a small dose of steroids.

She's been on Hills Prescription i/d (chicken stew) for maybe 7-8 months, which seems to have solidified her stools a bit, but in those months she has still lost another 1/2 pound. About a month ago the vet put her on steroids (prednisone) to suppress her immune response so she wouldn't have so much inflammation. They tested her blood to make sure she didn't have other health issues that would worsen with the steroids, and everything else seems healthy. The steroids have made her stop pooping all over the apartment and my furniture, but she still goes outside of the litter box all over the floor of the room the litter box is in.

This whole experience has been incredibly stressful for me, and I am wondering what her quality of life must be and if she will ever improve and start gaining weight again, or if i should start thinking of euthanasia. I was wondering if any of you have any advice or input, have experienced something similar with your cats, as I am feeling quite hopeless and overwhelmed right now. Any help would be greatly appreciated. Thanks.