Blood test @ 7dpo....too soon

Renae • 💙 '09....💙 '11....💔 '14.... 💔 '14....💔 '15....💔 '16....💔 '17....💜 12/12/17
I was wondering if I could have gotten a fulse negitive on a blood test @ 7dpo? I was cramping pretty bad that wk and went to my dr who ordered the bloods to check my levels etc and today when I rang to get the results the receptionist told me my dr had seen them and there was no further action required. I took a hpt on sat night making me 10dpo and got a very faint positive, today makes me 12 dpo with AF due on wed 5th. Could it have been to early for a blood test to register?? Any advice would b great