Your post is dated almost a year ago. Hopefully by this time you have decided what to do about a mastectomy, and are healing now.
I was diagnosed with DCIS, state 0 about six months ago. Even though my tumor was on the large size, my surgeon didn't hesitate about recommending a lumpectomy. He did mention If I had chosen a masectomy I wouldn't need further treatment, though. The operation was fast (only 1/2 hour long!), but had seven weeks of daily radiation radiation ahead, in another town.
Few side effects, and I chose no follow up hormonal therapy.
I'm not sure why your surgeon would recommend such a drastic move for DCIS, stage 0. Have you had breast cancer before? You must have a cancer history in the family? I know women who have chosen more radical surgery just because they don't want to WORRY about it coming back, and they have reason to worry. If you are still unsure, I'd get a second opinion. The good news is that reconstructive surgery has come a long way, and may not be as bad as you fear.
I send my very best healing wishes to you, and hope that it has been resolved, with you back on the road to recovery.