@KimF
As you can see above, there’s no simple answer to your question. Many face the same dilemma, and make different choices. My surgeon recommended a mastectomy, which I had. A later discussion with my oncologist about the possibility of having the other breast removed elicited his opinion that cancer might as easily appear elsewhere in my body as my other breast. I’ve stayed with a single mastectomy - I’m comfortable with that but the following may be worth thinking about.
Have you discussed your anxiety with anyone? It’s pretty natural at this stage but if your anxiety is particularly high, or you are prone to it, that’s worth taking into account.
Do you plan to have reconstruction? If so, what are your options and surgery implications?
A lumpectomy now does not preclude further treatment when you have had more time to consider all your options and become more accustomed to your diagnosis. It’s always a shock, in spite of the stats, and making big decisions when you are in shock is rarely a good idea. Whatever you decide, it’s best to have no regrets.
Best wishes.