How soon does a pregnancy test show up positive?

Carine
My next period is supposed to come in 7 days. I've been having a lot of early pregnancy symptoms such as sore breasts, morning sickness, bad cramping, and fatigue. 
How soon can a test tell if you're pregnant? I took a test 11 days before my expected period but it came back negative.
I'm getting really impatient😭 advise?!