Any time you have unprotected sex,
anytime, you can get pregnant. If you've missed your period, you can take a home pregnancy test, now. When you're young, your periods can easily change &be irregular... Even if they've been "regular". They can &will change &adjust.
If you're going to be fooling around &having unprotected sex, get on birth control, &use condoms. Every single time.
All it takes is one time &one little sperm.