Your breasts will grow when your DNA says they will. Just because you have started your period doesn't mean your breasts will just pop out. Your DNA says how you will look when, and since DNA combination from your parents is completely random there is no way to predict when they will grow. I could go into detail of the chromosomes and stuff in DNA but that would take to long, but i will say that unless your parents had the DNA customarily put together (i don't think they had that tech 13 years ago though) there is no way to know. Just wait a few years, or maybe just a few month!
Girls breast usually grow during Puberty. Female puberty can begin from age 8 to 15 or so but the average start age will be 10 - 11 years. They usually start developing breasts then but everyone grows at different rates.
The breasts of chickens.
When breasts first begin to develop, called budding, the normally flat-chested areas will begin to develop and grow. At first, the area around the nipple might seem a bit swollen or enlarged, and often become tender and sore. Then the actual breast will begin to develop.
Not usually no, as the changes to the breasts usually begin further into the pregnancy,.. the earliest breast changes are known to begin is 3 months. but then, this can be brought forward if its a second or 3rd pregnancy.
Projesterone
THey will grow whenever you begin puberty.
gynecomastia
Not usually.
Breast development usually begins anywhere from age 8 to 13, and they usually develop until your mid teens (usually if you started on the earlier side) to early twenties (more likely if you started later).
When your breasts get out, it is usually called a nipple slip or a boob slip.
Breasts begin preparing to lactate while the woman is pregnant.
Most females usually start hitting their growth at between 9 and 12 years. During this stage, hips broaden and the breasts begin to develop.