How do i know if my cat is getting batter or worse after catheter removal

My cat had two catheterization.. the vet said he has struvite crystals
The second time he had a catheter the vet said his bladder isn’t completely full but she put it in cuz he was urinating so little and struggling to urinate and i was scared
Now he had it removed one day ago and he’s urinating a little .. what should i expect in the next days? And when should i be worried
I’m worried 24/7 and there’s no clear info about this ):