NHS Choices provides some good information on risk factors here.
These factors do not mean you will definitely get breast cancer. Sometimes, people with none of these risk factors will develop breast cancer- we don’t know what causes the disease in all cases. Whether you think you are at higher risk or not, it is important that you attend your breast screenings and go to your GP if you experience any unusual symptoms.
Some rare types of breast cancer can have different symptoms, so if you are at all concerned about changes to your breasts, please make an appointment with your GP- if it is cancer, they would much rather catch it early and make sure that you have the best chance of successful treatment.