I am worried I might be pregnant...

So my partner and I have been pretty good about using protection and he never finishes inside me, unless he has a condom on and even then he still pulls out. But for some reason, today I'm supposed to start my period and I feel like it's not going to start.

Am I just worrying too much??

Who else has this happen to them, and what do you do to try and not stress yourself out? I mean I'm 18, but I'm too young to have a baby.

I'm also way too stressed to take a pregnancy test for fear of it actually being positive.

(Also my period isn't super consistent, but it's not often that I skip periods and having a sex life and missing a period is not okay with me and it's really stressing me out. I couldn't sleep last night.)