A doctor should have told you in advance about the Oncotype, which is now done on all ER+ HER2- cancers and determines whether or not chemo is of benefit. I am sorry you did not know about it. Get a copy of the report and read it carefully: there is a lot of information there. If you had a high score, it would help you to find out why. Was your ER% low? What grade was your tumor? The Oncotype report will tell you your risk with and without chemo and you also need to determine how much hormonal meds will reduce risk.

This happened to my cousin. She was actually initially told no chemo, which was not responsible in my view since the Oncotype had not come back.

I had the opposite happen: grade 3, highish ki67%, and mixed results for HER2. I also had lymphovascular invasion (lymph) , not good. But my Oncotype was low. This means chemo was of no benefit and maybe even more harm than good.

The fact that you had clear margins is great. But I have read that surgeons should not say "we got it all." Treatment is for stray cells with the potential to cause recurrence or spread. So glad your lymph nodes were clear!

I got 4 opinions and some retests. Keep going until you are sure of what you want to do!