Welcome to our community, and CONGRATS on being a 20+ year cancer survivor! I think they are beginning to use MRI more and more for screening in high risk women, but it is not the standard of care. I was diagnosed at 30 (now 36) and still get annual mammograms. I expressed the same concerns about the lack of effectiveness of mammograms for us younger gals. My surgeon still felt confident with it and never recommended anything but the mammogram. My other docs seemed ok with it too, so I made up my mind that since I do trust them, I needed to follow their advice...or find a new doc.
I would recommend that you consult a breast specialist, not just an oncologist. Your local hospital or university hospital probably has a cancer center, which may have a breast clinic. At my cancer center, the breast clinic sees women with healthy breast conditions (non cancer) and high risk women. They will probably want to follow you more closely.