I need advice! I think I'm pregnant

Hi! I have the nexoplanon implant and I've been having unprotected sex with my boyfriend since November. I've had the implant since July 2014. I get the birth control taken in July 2017. I always worry that I am pregnant because I am 17 and obviously don't want a kid. I know this birthcontrol is extremely effective and it hasnt moved or bent. He also doesn't cum in me. But I'm thinking thag it might have some how gotten in my a little bit. I am just looking for advice so i stop stressing myself out before my period. I am supposed to be getting it in 3 days