Advice please!!!

So I'm sorry if this is lengthy but I'm getting scared. I've missed two periods now, which by my lmp dates me 8 weeks pregnant. Here's the catch, I can't get one positive urine test. I went in yesterday for blood work but does anyone know why I wouldn't be getting a positive test? I'm waiting on the blood results but I'm going crazy as to why this would happen or if I'm pregnant at all. If I'm not pregnant, while unplanned and a surprise, I would be a little disappointed and going crazy again as to why I've missed two periods when I never have before other then my first pregnancy. Any help would be so greatly appreciated, baby dust to everyone!!