My 19yr old daughter gave birth 11 months ago and still hasn't had a period. She's not breastfeeding and not pregnant. Is this normal?

See a Specialist. Most women who are not breast feeding will get their menses by 3 months and maximum 6 months. Please see a doctor for some hormone tests.
Not normal. Studies show that most nonlactating women will not ovulate until 6 weeks postpartum. 70% have had return of ovulation by 12 weeks. This would then be normally followed by menstruation. 11 months is significantly longer than this timeframe, and deserves and evaluation by a doctor. .