1st, as most of us would say, sorry you joined our club but, glad you found us. Also, there are a lot of positive and long living survivors here.
The normal protocol is a 2nd TURB because you want to be sure "margins" are clean and be sure this hasn't progressed. While it sounds that is the situation you WANT to be sure. No matter what with your DX I would want a 2nd opinion pathology wise. Second, with "some" high grade cells many URO's would rate you as high grade (I am not a doctor but I am just echoeing mine). BCG is a standard treatment for high grade, stage TA, T1 cancers. Stage 2, 3, or 4 most will encourage a cystectomy. BCG is certainly a viable option from what you have described.
Personally, I would get a second TURB and possibly have it done at a major cancer bladder center. While this is very treatable, many URO's see far more prostate cancers than bladder. I got lucky with mine in the fact he does a lot of BC and actually interned under Dr. Lamm many years ago. If your insurance and accessability travel wise make that possible let the board know what area you live, someone can recommend a good center. I live in Texas and my backup has always been MD Anderson in Houston. I won't hesitate should I have more problems. I am 5 years cancer free so I may be one of the lucky ones, remembering everyone is different and my aggresive tumor was found early.
Keep asking/posting! We all have been down this road with many forks. You'll find help!