Breast size is mainly related to daily diet, congenital genetic factors and endocrine hormones during development. 14 years old is in the puberty development period, breasts are still in the process of continuous development, due to individual differences and genetic factors, the development situation is also different, as the age grows, breasts will slowly become larger. Massage can be done in daily life to stimulate blood circulation in the breasts. Maintain balanced nutrition, eat more protein-rich foods such as eggs, fish and shrimp, soybeans, etc., eat more vitamin-rich vegetables and fruits, and do more chest expansion exercises to increase the chest muscles. If your breasts are still small in adulthood and you have secondary development after pregnancy, there is no need to deal with it if there are no other abnormalities. If the secondary development does not achieve the effect you expect, you can have surgery after breastfeeding to avoid affecting breastfeeding, and you should go to a regular hospital for breast surgery or plastic surgery. Under the guidance of a professional physician, choose a reasonable treatment method, such as surgical treatment, including autologous fat transplantation and breast implantation. Avoid blindly believing in folk remedies and abusing drugs containing high hormones, which may cause adverse reactions.