Should I consider it stress or pregnancy?

My period is 7 full days late as of the 29th. The end of today (the 30th) will be 8 days. I'm usually so regular it's like clockwork. I can pinpoint it down to the day. I haven't been late for even one day for at least the past year and a half (as far back as I can look in records). Right now, I have none of my usual period symptoms (sore breasts, spotting a few days before).

I had one stressful day at the start of this week but it was quickly over and I've been fine since. My period was actually already 2 days late before the stressful day, I just didn't realize it yet. I noticed at about 4 days late but just figured it would come. However, here I am at 7-8 days and not a sign AF is coming.

My husband and I used protection without fail but I guess anything is possible.

How long should I blame the stressful day before I give in and take a pregnancy test? I know I could test now but I just don't want to jump the gun. Stress has never delayed my period before so I really don't know how to look at this.

Thanks.