I'm experiencing urethral pain and bladder pain. Frequent urination and Sudden urge to urinate. For 18 months. Not uti. Intermittent. Possible cause?

See a urologist . Long standing issues like this require in person evaluations. Please see a urologist. .
Like UTI, but not. There are conditions that present and feel, for all intents and purposes, like a urinary tract infection but in fact are not. Interstitial cystitis, for example. If your symptoms have persisted this long and have not been repeatedly attributable to a UTI, then you need more investigations into cause. You should consult with Urologist and Gynecologist, if you haven't already.
Lack of care... 18 months? Really? ..and you want a diagnosis online today? NO. See a urologist ASAP! You will need cystoscopy and ureteroscopy in addition to urine analysis, culture and STD screening.

Related Questions

What could be cause of bladder pressure? Negative UTI, no pain or frequent urination. Have IUD but it's in place.

Needs a scan. Very difficult to comment without further history and examination. You may be constipated which can in turn cause pressure on the bladder. There may be a fibroid in the uterus. You will need to see your doctor to get an X Ray and/or ultrasound scan arranged to see what's causing this. Read more...
Bladder pressure. it is interesting issue. It will be important to know your obstetric history. some time people with weak pelvic floor can feel the pressure. It will be important to see your GP to make sure that there is no uterine prolapse (partial) which can cause the pressure sensation in absence of these symptoms. A doctor review is recommended as it may need an internal examination. Read more...
See below. In a young female with bladder pain, discomfort, and/or pressure in absence of a UTI and with a fairly unremarkable urinalysis, the most common cause would be "Interstitial Cystitis" (aka Painful Bladder Syndrome). Often associated with variable degree of urinary frequency and less often pain with intercourse. Other possible causes would include gyne-related problems (e.g. fibroids, endometriosis) Read more...