Chronic Constipation Problem

Baby Keona has been always constipated. We have already changed her diet to fiber - rich foods and increased her fluid intake but it did not work. Sigh. I'm always concerned with this poop problem of her because it will trigger infection (UTI) because she is having ureteral reflux according to her pediatric nephrologist. We have tried feeding her oatmeal, citrus fruits like mandarin, pomelo, ponkan, orange and other high fiber fruits such as grapes but it's still the same. We have also tried prune juice. It just solved her poop problem minimally but not totally. Whenever she's hard up defecating, we have no choice but to put on those soppositories which I dreaded because I'm afraid she'll become dependent on it.