I am a 59 year old, female with a very similar situation to yours. My tumor was 1.8 cmm and was estrogen positive and node negative. My OncoTypeDX test showed me with a 3% improvement in my 10 year reoccurance rate which was 15%. I decided against chemo and opted for Arimidex and lifestyle changes instead. My oncologist said that I needed to be sure that if my cancer came back, I would not feel that I did not do everything I could. I asked if it could come back even if I had chemo and she said "Yes". That was all I needed to hear.
This is a very personal decision with no guarantees either way. That's one of the most difficult parts of this disease. My decision felt right for me and I am at peace with it. That's the most important thing. I would recommend following your instincts.
Good luck and God bless you in your journey.