hey hun, i'm pretty much in the same boat as you just 1 day behind, my periods have always been like clockwork, they screwed up and didn't come after i had my daughter but since 3 months ago they have been fairly regular and again like clockwork but this one is 4 days late - i have tested but it's coming back negative
Try testing again in a week if nothing they recommend you make an app with the docs where they will prob test you to see if your pregnant (lord knows why but they seem to be better at reading pregnancy tests no matter how faint!)
Also are you testing your first urine of the day? that's the best time to detect early pregnancy as the hormones decrease throughout the day.
hope this helps and keep us posted
