Molly,
Someone with more experience will eventually enter with a better answer. For now, I'd just be sure your URO is up to date with your past. Taking BCG includes a risk of contracting TB, albeit a small risk. Hence the urine test before instillation to be sure you don't have an infection. After the instillation they will tell you to call if you have anything higher than a low grade fever (fever being opne of the possible side effects).
As far as 6 treatments. I have read about a small minority that believe 6 is enough. A large majority believe in a "maintenance" protocol over several years. Some have had once a month for a year (I believe some of our Canadian friends get that type). Mine had me take 6 weekly, 6 off then 6 more and that was it. His reasoning was each instillation incurs some risk. I am almost 2 years out and clean.
Basically, everyone case is different from types of tumor, size, quantity etc. I like a doc that is cautious, conservative and up to date which yours sounds like one. Keep posting and someone will have more insight, be an advocate for yourself and read what you can.
Am enclosing a link for one of the better files on BCG:
www.urotoday.com/prod/pdf/eau/05_TaT1_Bladder_Cancer.pdf
Alan