You're not the only one who wonders how this guessing game is supposed to be played. For starters, get a copy of your pathology report and take a look at the current national breast cancer guidelines, which were posted by Rhonda:
NCCN Practical Guidelines in Oncology= V 2.2006
http://www.nccn.org/professionals/p.../PDF/breast.pdf
Also, ask your onc to go over your risk using the online Adjuvant! website if she hasn't already done that with you as it can provide you with a rough idea.
Hopefully those with tumors under 1 cm or your age may also respond to you here. If you can add more info about your hormone receptors or your tumor grade that might help.
AlaskaAngel