So sorry to hear of your complete surprise diagnosis! It is a shock for sure. My situation was that I needed a bilateral lumpectomy, so I went with the recommendation of the breast surgery. Mostly I am happy with that decision. I would never had wanted to be lopsided as these days I have larger breasts, so if only one breast needed to be removed I would have pushed very, very hard to both breasts removed. I think it is possible through the public system, not sure though! Perhaps another forum member knows?
Sometimes tossing ideas around with other women here can help you clarify what will best suit you. It can be an isolating time, so if you need to discuss with others hop on here any time, and mostly someone will come on with their two cents worth.
You have had a long wait to get to the surgery stage, but that can be the case in the public system, unfortunately. Sorry to hear one tumor is twice the size. I also had a long wait, and I am pretty sure you will be OK, as was I.
Best wishes and you are in good company here on the forum. Just sorry you find yourself here. xx