Help! 😩

Okay, so.... I'm about 20 days late for my period. The past three-four months, they've been on the 24. I just got off of the Nexplanon back in March. Had a period in April, May, and June. I had (drunken) unprotected sex, like, June 31-ish. I took a pregnancy test about a week ago, and it came back negative. Should I be worried? Are my periods just a little off because I just got off birth control? I'm not really having any strange symptoms. Hungry and tired a little more than usual, but not much else. Occasional nausea. Maybe I should go to the doctor and get some blood work?