Do you have pus cells and epithelial cells in your urine? Not all bacteria grow easily and lab tests are short duration as well. Bugs will only grow if they are planktonic in the urine.
Look up 3C and also look up biofilm infections in the bladder. Will your Urologist give you antibiotics to see if this helps and will they combine this with Hipprex?
Do some research yourself and keep asking the questions