Sorry to hear your both having a rough time of it

I think if it was me I would carry on feeding her if she's happy to take it, I've found with mine they don't like critical care so the mushed pellets in warm water is always a winner, but they do like supreme recovery.
But to be honest if she's eating anything it's definitely better than eating nothing, so just give her anything she will eat
What antibiotics is she having? The antibiotics will generally take a few days to start working, so hopefully she will show improvement soon
If she's tried on a different antibiotic if this one's not working, it might make a difference as the infection could be resistant to the current antibiotics, maybe a swab would beneficial?
Does her wee seem at all gritty/chalky? I'm wondering if she has bladder stones, crystals or sludge which is scratching her urinary tract & causing the continuing bleeding?
As far as how long to fight for her, she will let you know when shes had enough, if she's still fighting & enjoying doing piggy things then I would leave her as she is, keep up the pain relief so her quality of life is good.
Maybe wash any veg she has & leave it wet, let her get in as much liquid as possible to keep her well hydrated.
Are there any classic signs of ovarian cysts (hormonal, hair thinning on sides, etc)? My 6yr old Ellie had persistent uti's & heavy bleeding & it turned out to be an ovarian cyst. She was however generally in very good condition otherwise & had hormone injections which gave her 2 extra years.
Good luck in your decisions.
I hope you can get her sorted, fingers & paws crossed for a full & speedy recovery.
Xx