@Mjames I had the same choice.
I had DD/E breasts.
My initial reaction was mastectomy, but after my first scans and biopsy I was convinced that it wasn't necessary and went with lumpectomy and bilateral reduction at the same time.
My reduced breast is a great size (C) and I have full nipple sensation, though it took a while to be less sensitive enough to touch.
However, the pathology after lumpectomy was much worse than the scans showed and I ended up with the decision again of whether to remove both or just one as I had to have a mastectomy on the affected breast.
I had an MRI to make the decision and it came back that the other breast was clear so I opted to leave it on, as reassurances from Oncologist and Surgeon suggested it was not a big risk.
I can always have it off later if I decide I cannot live with the uncertainty of the mammograms and Ultrasounds as my previous ones have not been correct.
I can't afford to have constant MRIs.
I am now pleased I did leave it on, having one natural breast is for me better than having none, and I did not think I would feel that way.
Sometimes you don't know how you will feel until you get there, so take the decisions slowly, and if in doubt perhaps leave it for another day.
I have put my name down for DIEP flap reconstruction on the public list and will have a 12-18 month wait. This gives me time to adjust to the mastectomy and decide if I want to go ahead with a big operation.
I cannot have implants as I am having a lot of radiation and my surgeon was against the idea.
Be prepared that the decision may be different after surgery, you may have to go back for more, so keep this in mind when making your decisions.
I really hope you don't but having to have a mastectomy later may mean that you would have made different decisions if you had known.
Good luck with making a decision you feel comfortable with, Jennie