Worried about pregnancy.

So I’m really worried, I’m travelling in Australia and I just met this guy & we started sleeping together. I had my period just over a week ago and my period tracker is telling me I am in my most fertile stage but I didn’t even realise I don’t check it all the time! I had unprotected sex 2 nights ago. I’m 18. By myself in a strange country. This guy lives near me back home but I don’t think he will want a baby yet as he’s only 20. I always said I wouldn’t get rid of a baby but this is freaking me out. How long do i have to wait to see if I’m pregnant or not?