Yes, 11 years is within the normal age range for periods to start in girls.
Most girls get their first menstrual cycle between 9–15 years of age, commonly around 10–13 years.
In the first 1–2 years after periods begin, cycles may be somewhat irregular initially, which is usually normal.
Health Tips
You should consult a doctor if:
• periods started before 8 years or not started even after 15 years
• very heavy bleeding, severe pain, or prolonged irregularity occurs
• associated excessive weight loss/gain or other hormonal symptoms are present.