19 weeks - concern

Ashlee
Sorry for the long story.... 
Hey all, so at my 12 week ultrasound they told me my baby had a thick neck and I had to do further tests for Down syndrome, those test came back as about 1/2000 so the dr said I don't have to worry about Down syndrome. But there may be other things that cause baby to have a thick neck, like cardiac or maybe some symmetry issues with facial features... But I have to wait for my 19 week scan to pick any of that up. 
My 19 week scan is on Tuesday and I'm starting to get nervous, anybody else had anything like this?