I can understand the stress. Most of us have been there at some time or oter. First of all, your team will want to do the best they can for you. The surgery will basically get rid of the cancer, any other treatment is really to mop up any stray cells to reduce the risk of it spreading.
One of our chemo group, the February Valentines 2013, had a similar situation. She had a WLE but they didn't get clear margins, so she had to have a cavity shave, twice. She was supposed to start chemo at the beginning of February. She eventually started in April, and has recently had her second year check up and is still clear of cancer. So please don't worry too much - although I realise you will.
I am stressing. I found my lump and first went to the gp on 22nd December. Having had two biopsies and two WLE I am booked for mastectomy on 17th March which means I won't even start chemo til presumably mid April time or later! Shouldn't I be having chemo earlier or isn't it detrimental to wait this long?