I feel like my heart has been ripped out of my chest

Katie
I toke 3 tests all came back positive for very excited but on week 6 I had some cramping and worried asked for a blood test, got a call this morning to tell me I'm not even pregnant. I'm in shock iv had all the sytoms positive tests but yet no baby. 
I don't no how I'm surpost to just carry on. 
I had everything planned how can I not be pregnant? Why is my body doing this to me?