Neurogenic Bladder. Overactive bladder!

Hi Doc I have been diagnosed Underactive bladder By doing Urodynamic Study my bladder capacity is 230ml but I am not able to hold 230 ml . Sensation - Normal Compliance- Normal Detrussor function only-Detrussor pressure went upto 2cm of H2O Flowrate - Low Detrussor Pressure- Not raising much wven with abdominal strain Fitst desire -135ml Normal desire 190 ml Strong desire -191ml Low capacity, Normal compliance, Normal sensation and feauture suggestive of UnderActive Detrussor Bladder I had to urinate often in 5 to 10 ml in 15 to 20 min if I hold the urine for long time it develops pain in flank . Dr has prescribed Alfuzozin Prolonged release tablet it doesn't seems to work rather it developed constipation and back pain I have a doubt do I have Underactive bladder or Overactive bladder