How big are your breasts meant to be at 12?

Breast size can vary greatly among girls at the age of 12, and there is no specific, prescribed size that breasts are "meant to be" at that age. Breast development is influenced by various factors, including genetics, hormones, and overall body development, and it can differ from one individual to another. It's important to remember that breast size is not a measure of a girl's worth or value.