I found this recently and felt it's a great resource. It really explains those long delayed recurrences. Being younger means this could be in your 40s or 50s rather than 70s or 80s and why they would recommend chemo.
https://www.cancer.net/blog/2017-05/understanding-risk-late-recurrence-breast-cancerOncotype dx testing might be an idea also. It costs a few thousand but a better predictor of recurrence and if chemo is of benefit.
Details of this is below.
https://www.bcna.org.au/understanding-breast-cancer/treatment/surgery/breast-cancer-pathology/However chemo should start within 6 weeks of surgery so your time frames are tight to explore options of testing if chemo would help.
Kath x