I'm sorry for your diagnosis.
I had a single mastectomy with axillary clearance Feb 2020. My surgeon wasn't keen on removing a healthy breast.
Also I think it was a case of wanting to get rid of the cancer quickly, recover and get on with Chemo and R/T.
2 years on now, and I want symmetry. I hated having one breast 18DD. I hated needing a prosthesis.
I considered going flat, but I have a bit of a fat tummy. So on to reconstruction.
So 3 weeks ago, I had a prophylactic Mastectomy with tissue expander, and Latisimus Dorsi flap to my original side, also with tissue expander. At present I have A/B cup nippless boobs. The size will be increased over the next few months.
I wasn't too concerned re cancer developing in the healthy breast, but it is one less worry.
Symmetry was my biggest concern. Flat or reconstructed.
Good luck with your surgery and recovery. And any other treatment that you may need.