Negative Test, 8 days late

AF is 8 days late, I'm normally a 28 day cycle kind of girl, my period is very very rarely late, and when it is, it's only by a day or two. Every urine test I've taken in the am has been negative, but I've had nausea, a day of bad fatigue and my temps have been rising over the past few days. I use OPKs too, and I really want to be pregnant, but I don't want to get my hopes up. Has anyone has a urine test come back positive this late in the game? I'm going to call my doc to order a blood test in a few days if I still come back negative.