I understand how you are feeling...it IS a shock to get such a diagnosis. You will find that the more you learn about it, and as time passes, you will learn to relax a bit.
You are very fortunate so far (doesn't feel like it, does it?) because you appear to have a low grade tumor, found very early. The reason for the 3 month checkup schedule is that these little devils can keep reappearing. If you, and your uro, keep on top of this, as you seem to be doing, they can be removed easily...or, if there were to be any progression, it would be dealt with early.
Please know that there are lots of people here who have "been there, done that." You can ask any questions and we will try to help you.
Sara Anne