4 days late according to glow...

Glow said I should of started Saturday, but here it is Tuesday and nothing. Not even spotting. I was having mild cramping in waves on and off (didn't have to take tylenol like usual) up till today. Today I woke up and have no cramps or anything whatsoever. I decided to take a CVS brand early pregnancy test and it came back BFN. Anyone know what It may be? Could I be pregnant and the levels aren't up yet? Or is my period late? I can't remember my period ever acting like this. Thinking about waiting a week to test again or until Saturday if nothing.