Hi - tough decision, and only you can make it. If you have a mastectomy, then you obviously greatly reduce the risk of breast cancer coming back in the same breast. I can't read a patholgy report very well - can't tell if there was node involvement. If not, then a mastectomy would also help preclude cancer spreading to other parts of your body. A lumpectomy, while less sure, when accompanied by radiation also does a good job. They are EQUALLY EFFECTIVE for preventing death due to breast cancer.
You'll have to decide how much of a risk-taker you are. Do you feel you could take a chance with a lumpectomy? Or do you feel you need to go for a more aggressive mastectomy, which comes with other physical problems (possible shoulder issues, numbness, body image, etc.)? If you're very small-breasted, you might actually have a better result with mastectomy and a prosthesis, implant, or possible reconstruction. Depending on how much more they have to take with the lumpectomy, they might leave you with a disfigured breast.
All of that said - personally, I opted for the lumpectomy. In the end they couldn't get clean margins, and I had a masdtectomy and reconstruction. But I felt the less aggressive surgery was worth a chance, at least.
Good luck with your decision - PJH