Girls lone?

My friend wanted me to ask this. Her length is really late and she is a virgin. There is no instrument she could be pregnant. She lives with her dad and does not similar to her step mom. My friend is 17 she is not stressed or sick. She does not play sports on any drugs. It's 1week and 2days late. That happen sometimes it's completely normal. If she misses it completely this month and subsequent month she should see a doctor.
If it is a regular assurance she should see someone. It could just be something hormonal approaching a thyroid issue.