Ananya
Blood in the urine and bladder spasms can be caused by lots of different conditions. Urine cytology has lots of false results, but is useful for screening test before proceeding with additional evaluation. It appears that your doc feels that the diagnosis explains your symptoms. That is a better diagnosis than bladder cancer.
Hopefully your doc has a plan to address your diagnosis, and resolve the bleeding and spasm issues, and look for other causes if you do not respond to treatment.
As with any medical issue, if results are not obtained, the question of 'Why not' will need to be addressed.
If you are uncomfortable with any aspect of your care, a second opinion is always a reasonable option.
Best,
Jack