@TR14L,
You're probably overthinking it.
However-- IANAD.
And exactly how the hell would your folks find out if you bought a pregnancy test? Take cash out from an ATM and go to a drugstore with your boyfriend and have him make the purchase.
Pregnancy tests are cheap and plentiful, and any pharmacist who blabs about your purchase to anyone, even your parents, or who gives you a hard time about it should lose their license.
I'm not kidding. Despite the current post-Roe shitshow, pharmacists are bound by confidentiality rules.
If for whatever reason you can't get a pregnancy test in town then go to another one, or have your boyfriend order one from Amazon.
Fear of being pregnant can screw with your head, make you anxious, and delay your period. It does you no good to avoid a test, particularly these days, where there are plenty of places where you can't get an abortion after 6 weeks. Waiting and wringing your hands with anxiety will make you miss that ridiculously tiny window.
What are the chances that you're pregnant? Probably close to zero--today.
But when your sex play progresses (and the chances of that happening are way higher than zero), you will need to be able to act. Make a plan now, even if you think abortion is horrible, and even if you don't think you'll ever use it.
Knowing what you will do, no matter what it is, will help your anxiety, too