New to this

I would go with the lumpectomy as your surgeon recommends. They aim for a one centimetre area clear of cancer/dubious cells margin around what they take.  If they don't get that in the pathology results, your surgeon will go back in and take a bit more on the dubious edge, again aiming for the clear one centimetre margin.  That happened with me with cancer cells near one edge the first time, and again there were dubious cells one and a half millimetres from the edge the second time, so at that stage the surgeon recommended a mastectomy, which I had.  All of this took place within five weeks.  I just was unlucky that the surgeon didn't get it all the first time, but pathology on what was removed picked up what the human eye couldn't see both times.  If you are really torn about what to do, either ask another surgeon for a second opinion, or have an in-depth discussion with your sisters, and then take the points that they raise to your surgeon for discussion.