I am a physician recently also dx with breast cancer. Without a family history of breast cancer (meaning for mother,aunts do not carry the brca gene), I would say your chance of breast cancer is low at age 19. Cyst and other benign conditions are more prevalent. Still, get the mammogram (ultrasound if anything looks abnormal on mammogram) and continue to do monthly breast exams. I usually tell my patients to be familiar with your breast b/c you see them more than any MD, and can pick up changes.