What's happening?!

So I know that eve is just a prediction but usually it's pretty spot on about when I start my period.. however, Im 8 days late.. I think it's just delayed due to stress because of school/work or because maybe I'm syncing up with someone or because I was actually early last month and it's just my body trying to get back to normal schedule... My boyfriend and I are extremely cautious when it comes to sex as we ALWAYS wears condoms and he always pulls out before he finishes.. I have taken two pregnancy tests just in case and both came back negative.. Im freaking out because this is the longest it's been and usually AF would have came by now... any advice or comments welcome! 😭