Breast development or changes is a complex biological process in that it takes place throughout a female's life. It occurs across several phases, including prenatal development, puberty, and pregnancy.
The process is mediated by an assortment of hormones (and growth factors), the most important of which include estrogen, progesterone,
prolactin, and growth hormone. Genetics also play an important role.
Exercises do help to improve strength, posture and overall confidence of the individual however it may not be the be all, end all for your current concern.
Next Steps
Exercises targeting your upper body and your chest muscles like modified Pushups, planks, chest fly, and chest presses might help.
Shoulder girdle/bracing exercises and upper back exercises like T raise can help strengthen upper back.
Maintenance of proper posture is also important.
Get in touch with a good physiotherapist to guide you with an exercise program.
Have a healthy diet and lifestyle. One can probably add estrogen rich foods to your everyday diet in consultation with a gynecologist or physician.
Health Tips
Practice and develop self confidence techniques.
Consult aesthetic surgeon, if need be.