Is 32b small for a 13 year old?

"32b" refers to a bra size. Whether it's small for a 13-year-old depends entirely on the individual. Breast development varies greatly among teenagers. Some 13-year-olds are already well into puberty and have larger breasts, while others are still in the early stages of development. A 32B could be perfectly normal, small, or even large for a 13-year-old, depending on her body type and development. There's no single answer.