S., my daughter has urinary reflux that was diagnosed at about 18 months. Fortunately for us, an older cousin had been diagnosed, so I was able to get her treated quickly. We've been on Sulfatrim since then; my daughter is almost 6. While I'm not sure that's the right course for you, her rating has decreased from 3-4 on both sides to less than 1. At our last visit about a year ago, our pediatric oncologist was pushing the Deflux procedure even though we'd seen significant improvement; the people who did her VCUG in fact thought the problem was nearly gone. We decided to wait for another year with the guidance of our pediatrician; we both felt like the oncologist was possibly recommending Deflux inappropriately.
So, what does that mean for you? First, I would not panic about the Sulfatrim. You can get it for $4 in the easiest bottle to use at a Target pharmacy. She's not been exceptionally prone to any other illnesses, and the two or three times she's been sick, other antibiotics worked just fine. It's part of our bedtime routine, along with brushing our teeth.
I hope that helps. Let me know if you need more information. You have to do what's right for you, but I think that the small dose of Sulfatrim and its side effects are far less damaging than any kidney issues that could arise.