So sorry you have this extra worry. Your doctor will have all your information so will be able to give you your best options for you to choose from, but I can share my experience which is that I had my lumpectomy and axillary clearance just before Christmas before going straight into chemo. My margins weren't clear so I have opted for mastectomy which I will have after chemo finishes and then I'll continue with radiotherapy. I felt that I was covering all my bases by having the mastectomy, since I had lymph node involvement anyway. I have been planning on reconstruction, so will have a tissue expander in with my surgery.
So I'm sorry you have to deal with this extra burden and hope that your next appointment gives you all you need. It's a real rollercoaster at times. At the start I didn't expect the need for extra surgery, but I was fortunate to share a ward with a lovely lady having a second go at getting clearer margins, so I knew what was possible before seeing my surgeon afterwards.
Good luck and all the best from me too! Cheers, Meg :)