Thanks for writing to health care magic.
You have ruled out structural abnormalities and reflux of urine from all those investigations.
But is this urine infection confirmed from laboratory reports of urine examination all the time?
What was the urine culture and sensitivity report telling you.
Hope you got the complete set of investigations like MCU, DMSA, DTPA
Was your child's blood pressure taken any time?
Take basic precautions like
1. Ask the child to void urine frequently.
2. Ask to double void urine. Once she completes passing urine ask her to go and void urine once again.
3. Give her plenty of water to drink.
4. Avoid constipation
by giving lot of fruits and green leafy vegetables.
5. Do not clean the anal region from front.
Continue to ask further queries as required.
Hope this helps.