Negative blood test

Does a negative blood test mean I'm really not pregnant. I had a short, light 3 day "period" May 10th-13th and had a blood test done Wednesday and today they called and said it was normal, which meant it was negative. I also had a transvaginal ultrasound today and ask the technician if she saw anything and she said "I don't read them, but I think you're good" so does that definitely mean I'm not pregnant?