Pregnant with breast cancer..chemo or no?

Hello. I am 39 years old and I was diagnosed with stage 1/2 invasive ductal carcinoma in my first trimester.  Had single mastectomy last month in second trimester.  I’m am HR + HER2-, tumor was 22 mm, grade 2.  Lymph nodes were negative, margins around tumor clean. My oncotype score came back 29.  Odds of reoccurrence with just hormone therapy alone is 18%… if I add chemo ( which they are recommending) would give me a 15% benefit.  If I understand that correctly the difference between the two would be about 3%.  I’m struggling with what to do. Is 3% worth it to go through chemo for the rest of my pregnancy?  Any advice please.  Thank you