breast conserving surgery or mastectomy

Here is a little more detail from my pathology report. First though I'd like to mention that over the years I have had regular mammogram checkups, in fact the last one I had was in January  2016, 11 months before my biopsy. Pathology results oestrogen receptor - positive although only just 25%,Progesterone receptive - negative and HER2 status positive. Tumor size 28mm. Tumor Grade 3, Lymph nodes completely clear,, complete clearance re the tumor. Last week I had C.T Scans and Nuclear Imaging done. All good. Now I wait two more weeks to see Oncology. Seems like treatment will initially b Chemo followed by trastuzumab (Herceptin). My Specialist Surgeon is happy with my choice of lumpectomy.