Hi @ChrisF,
Welcome to the forum lovely. So sorry they have messed you around so much. This thing is hard enough to get through without plans being changed and lack of communication.
Unfortunately no body can make this decision for you. I expect it's just dependent on how you feel about the mastecomy VS lumpectomy. If your gut is swaying you one way even just a little more then that is probably best for you. Trusting your instincts through this is no mean feat either. Everything is just so confusing and you will second guess yourself all the time.
I found the original lump in my lymph nodes. No mammogram or u/sound could ever detect the primary breast lump, nor could you feel it. The MRI was the only thing to pick it up. In saying that though, MRI's are notorious for picking things up that may or may not be anything drastic.
My decision was easy. I wanted the lumpectomy unless there was absolutely no other choice. I had no reservations at the time and have not regretted the decision at all. I had two surgeries (one for clearer margins), chemo and rads.
Some people feel more comfortable with the mx to save worry at a later date. Statistics say that the lumpectomy with radiation are as good as the mx these days.
It is a difficult choice and I know none of that is particularly helpful in making your decision but rest assured we all understand the fear and confusion along the way.
Best of luck with your decision. I am sure there will be others along soon with their stories.
xoxoxoxox