scared of tampons

Okay so.. I have a really weird fear of putting anything in my vagina. Even tampons. I’m super scared I’m going to leak tomorrow because I have a field trip for school, so I want to use a tampon. I just don’t know how to not be afraid. The tampons I have in my house are way too big, I’ve tried inserting them, but I just break down and cry because they look too big and I don’t want this process to be painful. I’ve asked my mom if we could buy smaller ones but she says those are the smallest. What do I do? Should I just use a pad tomorrow? Tomorrow’s supposed to be my heaviest day...

edit: I am aware that the applicator doesn’t stay in