I would stick more towards Natural Balance, and my number one choice is Nature's Variety. Kibble does nothing for the teeth, the cat only crunches down on it quickly then swallows it, does nothing for the teeth.
Also, one meal of canned food is not really enough. Since you only feed dry in the morning and afternoon, the cats body has to use its own water reserve to digest the kibble, making them more dehydrated. What I do is feed a small handful of kibble in the morning, and then feed canned food throughout the day. My cats are annoying that if I only feed two or three full meals a day, they wont eat them, they eat smaller amounts throughout the day. I tried going kibble free for a month and a half, and my older female got stressed out and started pulling the hair off her stomach. (she is 7 and was not used to being without any kibble). But they have always gotten more canned than kibble.
And I agree, get your vet to run a culture, so your vet doesnt keep giving antibiotics for things that the infection isnt. I made that mistake, did a month of clavamox only to discover from a culture that my cat had a different infection and had to be treated with baytril.
Blue Buffalo has also been known to cause urinary issues. I used to work at a pet store a few years back and I knew of 3 people whos dogs got urinary crystals from blue buffalo.