How I can know I have breast disease?

Self exam/Mammogram. Ladies must examine her breast at least every month in different positions, in front of a mirror. Also once a year should be examined by a physician. At age 40 should start to have yearly mammograms. If the lady feels some lumpy area at any age must seek professional evaluation. Younger girls with lumps deserve at least and ultrasound. Review videos about self exam on the web.
Visit to your doc. I would recommend going to your primary care physician. Wishing you the best.