Help!! Could I be pregnant?!?? Need advice now!

So my boyfriend and I last had unprotected sex June 22nd, which was 18 days ago today.

My period was supposed to come 9 days ago.

The app says I have a 7% chance of being pregnant.

My period is never this late..

Sometimes im 1-3 days late but very rarely & it's been 9!

Help please!!!!! We've been together for 2 years & have been sexually active for about a year now. Mostly use pullout method.

SO says he's 100% confident he didn't cum inside me but I think he's just saying that so I'm not paranoid.

I'm underage and don't know how to tell my parents if I am.

Any advice how to tell them if I am?

Am I overreacting?