Ductal carcinoma grade3

I was diagnosed with ductal carcinoma grade3,  I had lumpectomy and sentinel node surgery on the 18th of October,  went for results on the 28th which showed I had precancer cells outside the margins,I was booked in for another surgery on the 1st November  for a reincision to remove the cells  Going back on the 15th again for results. Has anyone else been in this situation, maybe I'm overthinking things but I did ask the surgeon about what happens if there's more precancer cells and he said you could be talking a mastectomy as we only get 2 goes at this and also we cannot see where the precancer tissue is ,it only shows up under the microscope . I'll also find out what treatment I'll be getting as I'm still waiting on oncotype DX score coming back..