I understand your concern. Your present stage (I believe it is stage I) along with the findings of Her2 + and ER -/PR+ may warrant you to receive adjuvant chemotherapy with possible herceptin. Tumors that are larger than 1cm in the National comprehensive cancer network, are considered to benefit from adjuvant chemotherapy. You may also need hormonal treatment (like tamoxifen) after you undergo chemotherapy. Herceptin is a monoclonal antibody that targets the Her2 receptor and has been shown to decrease the chance of cancer recurrence and improve survival. I suggest you discuss all of these options with your oncologist.