Are you considered a late bloomer if you start having your period at 15?

No: The age for menstruation varies by ethnicity, location, & weight. Northern climates have later onset than southern for europeans, for example, while thinner girls start later than heavier. Onset after age 17 is considered late in the us.

Not necessarily: The term is a vague one at best and more often used by the lay public.Fifteen is at the upper end of the expected range for first menses. Delay past that point would be evaluated for any cause of delay although it can be later in normal girls.