Ann-
Glad the tumor is small and hasn't spread.

I think it is good to go with your "gut" for treatment. Only you know what is best in your situation. - I did exactly the same thing and DID have a double mast, even though my tumor was small as well and nonagressive.
We have a family hx and any woman that has had breast cancer (whether or not they have a hx) has a higher chance of br ca in the "good" breast. For me I felt it gave me the best chance for never having to face this again. I feel such relief knowing I have virtually no breast tissue left. By the way, my mom had a much larger tumor than mine and had a single mast, no other treatment. She is alive and well 29 yrs after her dx and is now 85. - I hope to live a long life like her as well.
Best wishes with your treatment.
Leea