From your description of the tumor characteristics, it is likely that chemotherapy may not be necessary. However, other clinical parameters must be taken into consideration. My advise is that you should see your oncologist for further discussion. Radiotherapy to the conserved breast is necessary as you did not have the whole breast removed. As the cancer is ER/PR positive, tamoxifen or other forms of hormonal blockage is very important and effective in the prevention of further recurrence. Lifestyle and diet is important as well but can never substitute the necessary medical therapy.