Is it just the birth control?

Heyyy guys, so I recently got the implant (nexplanon). I got it on January 2, 5-6 days before my period was supposed to come. They did a urine test it was negative. On top of the implant I was on the pill before, so my doctor told me I can keep taking it until the nexplanon started working which would’ve been 2 weeks. Same day I got my nexplanon I had sex(I’m still taking the pill). It was unprotected sex. Jan 7 comes and I didn’t get my period. I still haven’t gotten my period. I’ve been 16 days late. I took a test on January 17, it was negative. Am

I in the clear or should I test again ?