I am sorry that this turned out this way, I had hopes that this wasn’t cancer. I agree that doing what you can to make your body as healthy as you can and support your immune system is important. That being said, I believe that talking to an oncology nutritionist is best. Suddenly changing everything in your diet might not be helpful at this point because that has its own side effects.
Also if you are having other treatments besides surgery, heavy antioxidants can be counterproductive. My oncologist said within reason eat as healthy as you want, but don’t load up antioxidants because they might be counteracting the drugs you are taking to fight the cancer.
Also please remember skinny people get breast cancer too. Don’t shame yourself you have enough to think about right now. Somehow the stress and the treatments have a way of taking off a few pounds. Also I walked a lot to help keep stress and side effects to a minimum which always helps too.
Once this cancer is staged they will put together a treatment plan for you. Can you ask to talk to a nutritionist before your surgery? Do they have a patient navigator at your cancer center?

Yes, you said it — it really is a new normal. I like to believe it’s one that has the potential to be even better than the old one.
In my case, cancer was a huge question mark that led me on a deep internal journey.

Of course, any decision should be discussed with your doctors, but supplements can often be helpful. If you're starting hormonal therapy, they may recommend calcium, vitamin D, magnesium, and omega-3 — those are the ones I’m currently taking, with my oncologist’s approval.