Fear being diagonosed for the second time

I'm not even sure if I belong here or not.

Two years ago, less than a month after my first child was born, I was diagonosed with stage iii triple negative breast cancer in left breast. I did lumpectomy, ACT chemo, and 7 weeks rads. I have lymphadema in my left arm as a result. I am BRCA negative.

I delivered my second child this July, having had a clear sono of my breasts in late June. This past Wednesday I had some severe pain in my right breast (since decreased significantly). I called my OB concerned about mastitis since i am nursing. OB called me in and examined me, no lumps or clogged ducts, but sent me for a sono just to be safe.

8 weeks after my clear sono I have a 1cm mass in my right breast. Since my first cancer was triple negative (doesn't tend to reoccur in the breast) and in the left breast (breast cancer doesn't tend to switch sides like that) they believe it to be a second cancer.

I am sitting here in total shock and disbelief that:

1. I could be diagonosed with a second cancer 2 years after my first when I am under 35 and am BRCA negative.

2. That both my pregnancies could have resulted in breast cancer within weeks of having my children.

3. That I have a tumor that went from not existing on a sono to being 1cm in 2 months!

I was prepared for my triple negative cancer to spread. I was even prepared to have a second bout of cancer far off in the future (my surgeon and oncologist said I had the same risk to develop a second cancer as a woman who had never had cancer since I am BRCA negative). Heck, I was even prepared to get lymphoma at some point in the future.

But I wasn't expecting that I'd have a second totally new cancer following the same pattern as my first- immediately following the birth of my child.

I am awaiting having a biopsy on Monday. My family is still recovering from my last cancer treatment. I'm not sure if I can do this again. I was finally getting to the point where I felt like I could breathe again, that there was a chance I might grow old with my husband. Now this.

I don't know what to do.