I haven’t got my period this month yet.

So I’m 17 years old and me and my boyfriend have been sexually active. This app says that my period was supposedly start on the 7 of this month. But it says that I am late on my period. We have one more week left of this month and I haven’t gotten my period. What should I do? I need some advice or someone to talk to. I can’t really talk to my family about it or my mom because I am not close to them.