Hello,
Without examination confirmation of a diagnosis is tough but urge of frequent urination can be due to diabetes mellitus. Other possibilities are glomerulonephritis, pyelonephritis(inflammation of the kidneys),urinary tract infection, hypercalcemia ,hypokalemia(low potassium),hyperthyroidism, hyperparathyroidism, diuretic drugs and pregnancy(in females).
In my opinion, investigations like urine for pregnancy test, serum HCG levels,kidney functions, blood sugar levels, ultrasound lower abdomen ,intravenous pyelography , thyroid function tests and cystoscopy may be needed to confirm a diagnosis. I sincerely advise you to consult a urologist or nephrologist and get yourself evaluated so that a confirmatory diagnosis can be made.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Do you know how much urine you have left in your bladder after you urinate? The doctor would have given you a number of cc's "post-void residual" or PVR.