Is this normal or should I be worried?

Quick summary: basically my last period was on Feb 24- March 3rd. I’m on day 38 of my cycle, and my period has not came. I’m currently 12 days late. I took a test 6 days after my missed period. It was negative. My period have been irregular because I am on nexplanon(3 months being on it). However, I am still a little paranoid. My breast are currently very tender and I’m getting acne. Should I retest for pregnancy or is it the nexplanon doing its thing ? Need advice !!