Period late by 7 days but not pregnant?

Chilee

Hey hey so I’ve never missed a period before in my life but I’m a little concerned. I’m 7 days late and I’ve had three negative tests. I’m not sure what’s going on? But I’m concerned has this happened to anyone else. I did have unprotected sex over two weeks ago and I’m not pregnant because surely it would’ve presented by now.

Thoughts?