As Loiue said, so sorry you are with us but welcome.
I was in the exact same position as you are now a few months back. My breast surgeon told me he strongly recommended a mastectomy of my left breast after the two lumps were removed as I had extensive DCIS (pre-cancer) abutting the healthy margins and remaining in my breast. I did not need radiotherapy but went through 4 months of chemo before I was due for the mastectomy.
I agonised over having my right breast also removed all those months, I was constantly worrying that there may be pre-cancer cells present there too. Apparently it's not easy to detect DCIS other than with a biopsy which could be hit and miss. I eventually came to the conclusion that I would probably be worrying about this for the rest of my life. I wanted both of them gone.
I talked with my surgeon and told him I wanted a double mastectomy and at first he was not keen on removing a seemingly healthy breast but supported my decision. He did however insist I see one of his colleagues for a second opinion and he also recommended that both my husband and I see the Hospital Psychologist for counselling prior to my making a final decision and to understand exactly what I was in for. He told me that I was making a huge operation 'humongous' (his words) and I must understand this. I must admit that the counselling did help and I decided to go ahead with the double and for me it was the right decision. I don't regret it at all. Like Louie, I had immediate reconstruction so I woke up with new breasts.
Each of us has to make our own decision but I wanted to share with you my reasons.
Good luck with your decision. Sending you big hugs.
Janey xxx