Why hasn't Regesterone tablet induced my period yet?

If you had faint positive pregnancy test results and the ultrasound did not detect a pregnancy in the uterus, it's possible that the pregnancy did not progress or was very early on. So the bleeding could also be due to hormonal imbalances or other factors. Check with a gynecologist to be rest assured

Many factors can cause breast pain apart from cancer Hormonal changes like menstruation, pregnancy, and breastfeeding.. Injury or trauma to the breast. Fibrocystic breast changes or benign breast lumps. Breast infections like mastitis. Certain medications like hormonal contraceptives and antidepressants. Wearing ill-fitting bras or engaging in strenuous exercise. Most breast pains are not caused by cancer. Consult a doctor if you experience persistent breast pain. 

Puberty can start at different ages for different people and there is a wide range of what is considered normal. 
The ability to have children (reproductive maturity) usually occurs after the completion of puberty when the reproductive organs, such as the ovaries and testes, have fully developed. For most individuals, this occurs in their late teens or early twenties. However, it's important to remember that everyone's development timeline is different.