Why is my period late?

I’ve taken 5 pregnancy tests and they have all come out negative. I had sex last month and I was expecting my period last Sunday and I got nothing. I have no pregnancy symptoms, but I’m cramping a lot. Not to mention, I’ve been very stressed for a while and my diet has been kind of weird (eating a lot to eating too little and so on so forth). Is it too early to test or is this my diet and stress messing with my cycle? I’ve never been irregular.