A bit more info, as you mentioned the difficulties with your non-irradiated breast. My healthy breast just didn't feel right, neither of them did. No lumps but they ached, sometimes intensely. I had just been cleared to do mammograms every two years rather than annually, but went in at 17 months & there was the DC. After the mastectomy, my entire chest relaxed; it was quite odd. No more pain in my left breast, & as I mentioned, my right side is now free of the hitches it was having. The body is an amazing thing, way beyond my intellectual understanding.
I hope your rehab goes smoothly, & that your remaining breast calms down.