I’m not aware of any clinical trials that have shown a benefit to CBD for bladder dysfunction.
Meds have not worked? Have your tried a few? If you have not looked into Mybetiq and Trospium, it might be worth having a conversation with your doctor. Estim is also an option. There are also bladder PTs, timed emptying etc etc. If you are not happy with your urological medical care, seek a new provider.
Good luck.