No one can help you make this decision. It's just too personal. I would surely visit more than one surgeon, possibly three. I can tell you this: if you've been told a lumpectomy is OK, then it's OK. Many studies in the last several years show that there is no reason to have a mastectomy over a lumpectomy if your tumor type/location, etc.
Many girls do have mastectomies. There is no right or wrong answer. I was given the choice and chose lumpectomy. It's been 5 years ago. I had a small tumor and there was no reason to remove my breast.