Elevated Creatinine and normal BUN questions

Hello, I have a couple questions regarding my little girl. She's an 18 month old Bengal mix. Unfortunately when she was spayed at 10 weeks old the vet ligated one of her ureters and tied it off. So since then technically she only has one functioning kidney. She has been very healthy and has had no issues.  I took her to the vet at 8 months old to have her blood work done to see how the one kidney was doing on its own. At that time her creatinine was 1.6, BUN was normal (at the high end) and urine was normal. The vet said that the creatinine was at the high end of normal but nothing to worry about. I took her again yesterday to the vet and her creatinine was now 1.8, her BUN is normal and even lower than before, and urine is still normal. Her protein levels were a little high this time and they weren't before, but she is on a raw diet so the vet thinks this may be why. Obviously her creatinine is increasing but BUN isn't. She has no symptoms at this time. The vet doesn't think it's a big deal and to just watch it but I'm obviously worried lol. She's only 18 months old. There isn't any neurologists around me otherwise i'd see one. Just curious if anyone else has had similar experience or any input as to what I should do next? Thanks in advance for your help! 

Gosh, tough question. My understanding is that raw fed cats may have higher creatitine levels, but I don't think the levels should be rising. However, with only one functioning kidney, it's hard to know what's contributing to the higher levels. If the urinalysis was normal, then I suppose I would agree with your vet to not worry quite yet and keep an eye on it for now. I would probably retest every 6 months though...