Pregnancy after multiple miscarriages

Hadley • 18. Engaged. TTC.
I want a child. So badly. But I'm so terrified to be pregnant. I am taking a test in a week. But it's so scary. At 15 I lost my first child. She was a stillborn. Ever since, I have had miscarriages. 4 to be exact. 
Does my first pregnancy have anything to do with this?
Also how can I calm down in case I AM pregnant.