Hi there!
I am in the same boat except I was cancer free for 7 years before finding a new primary in the other breast. I had extensive (9cm) DCIS in 2003 at age 35 and had a mastectomy and reconstruction (TRAM) but no chemo or radiation nor hormone treatment at that time. The second diagnosis was in 2010 at age 42. This time it was 2.5cm invasive ductal carcinoma. No lymph node involvement. I had another mastectomy, lat dorsi with implant reconstruction, chemo (4 x TC) and I have now been on Tamoxifen for the past 7 years. I have recently found out that I have a gene mutation (PALB2 rather than the more common BRCA 1/2).
Apparently there is no difference in the survival rates between people who have mastectomies and people who have lumpectomies and radiation. I could have had a lumpectomy but after already going through it all once before, I didn't want to have to worry about a possible third diagnosis and so went for the more radical decision of a mastectomy again. My surgeon was 100% behind me.
Best of luck with your decision. If you want to chat any time, PM me.
Louise :)