New to site Oncotype issue...help

New to site and was diagnosed with invasive breast cancer end of March. Had bilateral mastectomy in April. Was told by surgeon margins were good. 2 tumors removed biggest one 4.6 cm. Saw oncologist first of week . Onco score 19. Normally would not need chem With this score. Oncologist  said due to size and grade 3 she would reach out to colleagues and call me with thoughts on needing chemo. She was not sure how big an impact chemo would have. Anyone experience this ? Don't won't to undertreat but definitely don't want to over treat. Will be having radiation and hormone therapy. Thank you for your support.