I take Yaz too, but I'm very careful and even use an alarm so I don't forget to take it on the right time. But idk, I hear so many stories about getting pregnant while on BC that every end of the month I get kinda worried
If it's bothering you, then insist on a condom. I can't imagine how much fun you'd be having when you're there worrying about getting pregnant, and then worrying some more after that as well til your period finally turns up.