Hello.
Im so sorry to hear about your cats.
Fip is such a devastating disease. There is now finally hope with the advent of the Bova GS – 441524 treatment. I think that Stokes Pharmacy has a very good write up on this if you want to see their website. I also know that multiple other manufacturers now make this so you can shop around for a price that might work for you. I ordered from chewy last week to get this medication overnighted to us for a cat.
Good luck!

Hello,
The assumption is that the labored breathing is due to the current and concurrent medical conditions. If that is the case then what are you hoping to gain by spending more money on a disease that sounds like it is in the end stange?
Where are you ready to say goodbye?
Has anyone spoken to you about the place she is at and the possibility of this all being futile care?
I’m not trying to send like I am not empathetic but there is no amount of money that will change this nor change the fact that you will likely have to say goodbye with a very painful decision soon.
Please ask a vet to be honest with you and not make this about the money that you cannot afford.
I’m sorry. It sounds like your cat is suffering and this is not curable. It’s ok to let her go. She was loved. You did everything you could. Try to be at peace with that.