Could I be pregnant???

I got the Nexplanon arm implant birth control about 5 days ago and I just had unprotected sex and he came in me. I was told by my doctor when I got the implant that, because I got it at the end/beginning of my cycle it should start being effective immediately but I’m just a little worried... what do you guys think? Should I get a pregnancy test? I just don’t want to worry my parents because I’m only 17...