Help docs! how to tell if i have breast cancer?

See your doctor.: Usually breast exam and screening mammography (x-rays) are first step. If something is suspicious you then get a breast biopsy by a surgeon that is then read by a pathologist to determine if there is a cancer. Women your age usually have masses that are not cancer, but it is very important to follow up with doctor to make sure. You don't really know until you do the above.