When to began getting cancer screenings?

Breast size is irrelevant for breast cancer risk.

Unless it is your father that was diagnosed r he has been genetically tested, the breast cancer history on his side of the family should not effect your risk

At 19 your risk is 1 in 1.3 million.

Screening starts at age 40 or, if you have a close member of the family diagnosed, when you are 10 years younger than they were at diagnosis.

Your doctor will most likely send you for breast cancer screening when you are in your 30's

Assuming you mean breast cancer, screenings usually start around age 40-45. If you have a family history involving at least one close relative being diagnosed under age 50, you should discuss it with your doctor.

Consult your family doctor and have him tell you the best course for you. He can also arrange for genetic testing to see if you have an elevated genetically linked risk of cancer.

See a Gyno doctor, tell her, see what she thinks.