False Negative ?

Hi everyone, so the other day i missed my period, i was on day 2 of a missed period and I took a pregnancy test and it was negative. Today I still haven’t gotten my period and I’m now 4 days late.. I use the Health app on my IPhone and it’s pretty accurate to when I will start my period. I usually always get it the day it says I will start.. but no period.

I usually always get my period on time, but I had a month about a year ago where I skipped it completely and I wasn’t pregnant. Everyone said it was from stress.

So I’m just winding if there’s a chance I can still be pregnant and I got a false negative and it was too early or if maybe I just skipped my period this month from stress ?

There’s also a chance that I have endometriosis. So that’s a factor as well.

Would love any information or input !!💖