Amenorrhea (no menstrual period for three consecutive cycles) in an athletic woman with low body fat ratio such as a dancer, runner or professional body builder is associated with low Estrogen. Estrogen is crucial for bone health. Please speak to your doctor regarding treatment options that can prevent bone loss.
frequently starting low dose oral contraceptive can provide sufficient estrogen to maintain healthy bone mass and restore regular menstrual cycle.
Also since we are on the topic of breast cancer, I wanted to encourage your to perform regular, monthly breast exams because 1 in 8 women will get it in her lifetime, know your body and protect yourself! This is a link to a video on yourtube that demonstrates exactly what to do