Could i be pregnant? Or is there something wrong?

Hi y’all! Okay so i am 8 days late today and i took two test by “first response” when i was 5 days late and it said i was not pregnant. So could i maybe have taken a test too early or could i have a health condition going on?? I have never missed a period before and have been on birth control since i was 14 (i am almost 20 now) i switched from the implant to the pill back in July and haven’t had anything irregular until now and I’m freaking out that if I’m not pregnant that something is wrong. I need advice