HER2 Testing & Breast Cancer Diagnosis: A Patient's Experience

Question
I had a core biopsy of my Right Breast on Dec. 11, 2008 that pathology report indicated showed a low grade (1) IDC and a high grade (3) DCIS.  There was no ER/PR or HER2 testing done and I was led to believe that I wouldn't need chemo due to the size.  As a result I delayed the double mastectomy I had decided on (due to hyperplasia throughout my left breast and dense tissue and other calcifications in the right) in order to complete a work project.  I had bilateral mastectomies on Feb. 3, 2009 and learned on Feb. 14th that the primary tumor area was HER2 +3 overexpressed.  They found a micrometastasis in my sentinal node (6 others were clear) and now am looking at a far worse prognosis.  The core biopsy maximum size of the tumor was 0.7 cm and by the time of the mastectomy had grown to 1.2 cm.  
My question is this - do they do HER2 testing of core biopsies?  It's too late for me now, but don't they get enough tissue to test for this?  Given that HER2 overexpression is one of the handful of primary determinants of both prognosis and treatment, shouldn't that be tested as soon as possible?
Thank you SO much for your help!

Answer
Yes it is possible, but I do not know what resources this laboratory had at the time. We are in this matter at the cutting edge of technology and it takes time (and money) for laboratories everywhere to follow the leading ones. Breast cancer is always a potentially deadly disease and should have the highest priority so it is most unfortunate that your work delayed your treatment. However it is quite possible that cancer existed in your sentinel node already at this earlier date.