It's absolutely your choice.
I've just recently had my 3rd surgery in 13mths due to breast cancer in both breasts (diagnosed at different times) & am awaiting results - again!
Both times recommended surgery was lumpectomy - last one however found a large area of undetected high grade DCIS in the surrounding breast tissue of the tumour so re-excision was required.
When I was first diagnosed I never considered having a mastectomy because I thought it was too drastic - but now I can totally understand why someone would choose this option :)
If you do choose to go down the mastectomy path just be sure to allow yourself enough time to research, find the right surgeon & ask questions so you can make an informed choice.
Mel xx