A Ta tumor is non-invasive superficial bladder cancer which is typically graded by cancer cell differentiation as either Grade 1, 2 or 3. The least agressive and least invasive of these cancerous bladder tumors would be a TaG1. From what I understand you don't even have bladder cancer, but a no grade transitional papilloma, which has a 7% chance of recurring as a cancerous bladder tumor. So, your not even on the scale yet! A T1 tumor has already invaded down trhough the first membrane in the bladder, you definitely don't have that - couldn't because you don't have cancer.
If in the 7 out of 100 chance you do recurr with superficial bladder cancer, then you can worry about the stage/grade. Sounds to me like your doctor is even overkilling your treatment by treating your papilloma like cancer.
YOU DO NOT HAVE CANCER RIGHT NOW! Beat that into your head