Bladder neck obstruction is idealy diagnosed via vedio urodynamics or combined MCU and urodynamics test. I hope urologist to whome you are consulting must had these test before making a diagnosis. Hydronephrosis is definite a serious concern. You may not feel any difficulty during voiding as long bladder is able to compensate by creating high pressure. This high pressure in bladder lead to hydronephrosis, progressive kidney damage and pain at groin or lower abdomen. Bladder Neck surgery at young age or before marriage or before having any kid, is to be avoided ( although best relief and cure is provided by surgery only) and condition can be managed till then by medicines.