Katie - ditto to what everyone else said. Get a second opinion at Sloan, also I know it's only a few weeks away but push to get in sooner, ask if they have any cancellations. Secondly, if you're at Sloan it would be a comprehensive team looking at you ( though the focus at this point would be MO, and RO) you should very much in my opinion have chemo. Radiation is localized to the area - chemo is systemic (works throughout your body) on the off chance you have a stray cancer cell moving about this should kill them. Three nodes whether encapsulated or not is nothing to sneeze at. Your lymphatic system runs paralel to you circulatory system and cleans your blood. Therefore it has access to everywhere. In light of this chemo should be offered as well.
I had perineural involvement, one node involved with a small amount of ECE - I had the works for treatment - they even gave me bilateral rads.

Push for more. Hugs and best of luck... Seriously call them daily to see if there are cancellations.