Hi TNH, sorry for your troubles.
To echo what wise Bev said, it really is a crap shoot. We've known people who defied the odds both ways....those with DCIS that developed into stage IV and those with giant tumors or lots of positive nodes that went many years or a whole lifetime remaining cancer free. And even if you took 10 of us with a stage IIA/ 2.5cm tumor like I had, no way to know who of us will remain cancer free or who will get a recurrance. The stats can only predict what should likely happen, but as we all know, cancer is cancer and does not play by the rules.
I am always in favor of second opinions but in your case, surely you followed the best recommendations and the most prudent medical advice but your cancer did not follow the rules. Try not to blame your self for not doing more or enough, and hopefully there is no regret for the medical decision that were suggested.
I once knew of another gal who had DCIS and did a mastectomy plus 8 rounds of chemo...more chemo than even recommended for stage I or stage II (and she was stage 0!). She shopped around for at least 3 doctors till she found one who would 'go big' with 8 doses of chemo, but alas, 4 years later, she also developed stage IV cancer.
We also know of a gal (who does not post much here anymore) who had stage II in her 30's and a couple years later got it back in her sternum. She was treated with rads and is now about 20+ years cancer free!
Just keep making the best choices you can make with the information you have and don't look back on the what if's or should have beens. And keep us posted!