How early is to early to test? Need answers

Okay so, on Sunday I got a blood test done in the ER for pregnancy just incase (I was in for my heart).. and it came back NEGATIVE. Ive been TTC for 9 months now and I really feel like this months different..

My period isnt until the following Saturday/Sunday (its tuesday now)..

Could the blood test be false negative because it was a week early or Am I really out for this month?