Bladder stones are serious and can lead to a like threatening urethra blockage that requires emergency surgery.
I would feed only what your vet recommends, does he have a nutritionist he works with or can refer you to? In case you want to try homemade.
Wysong also has a prescription food http://www.wysong.net/veterinarian/ Ask your vet if it’s an option, if you like the ingredients.
Consider consulting a specialist for more treatment options including diet choices.
In the meantime I would feed the prescription food, cooperate with testing and evaluate the results and go from there.
PS: check out Urate Urolithiasis http://www.vetmed.ucdavis.edu/vmth/small_animal/nutrition/client_info_sheets/uroliths.cfm
Also I have found the blogs at this site helpful, in fact I found the above link there http://skeptvet.com/Blog/2014/02/nutrition-resources-for-pet-owners/
