Should I take a Plan B?

So I had a Nexplanon put in my arm three days ago. I didn t have difficult periods, I got it solely to protect me from pregnancy. My period ended on the 8th and I got it on the 13th. So my doctor told me to wait three days before having unprotected sex. So my boyfriend and I had sex this morning, unprotected and he came inside of me. So me being the worried little wart that I am, I looked into it to see if it needed to be 72 hours exactly because technically it wasn t, but everyone is saying that it doesn t become effective for a week. So... I m freaking out. I don t know if the Plan B hormones will react with the Nexplanon hormones and mess up my system or anything but I mean also really scared that I was not protected because according to my period tracking app, it s also the first day of my ovulation cycle.