HER2 Stage 1 IDC Help!

Comparing to most of you, I am probably a lucky one. Early discovery of about 1.0 cm IDC near nipple, I opted for mastec. Path report: ER/PR +, no node problem. Then I opted for no radiation and no chemo. I started Tamox three weeks ago, right after surgery. Since I am HER2 +++, should I stop Tamox and go for Herpectin/Arimidex instead? All papers on Herpectin are on patients with worse stages; in fact, I would not be qualified for the study. My question is whether I made a mistake and should now stop Tamox and go for Herptin/arimidex regimen? I could not find any paper reporting results on non-metastatic BC with Herpectin as the monomedical adjuvant for cases like mine. Please help me to make the decision. My onc says its up to me.