Period late?!?

My period is 13 days late according to the eve app
I'm freaking out at the moment to be Honest and I know that doesn't help the situation
I went on holidays and had sex whilst there about 5 times, all with condoms
I was due my period about a week after my return, but I've heard flights can mess with your periods? Does anyone know if this is true??
I'm 18 and I'm really freaking out, I don't even know if I want to have kids at all and I know that's an outcome that might not even happen but I can help but think what if??
Advice? 😓😓😓😩😩😩