Down syndrome ?

Has anyone ever had the Down syndrome testing during pregnancy and the results coming back normal but still had a baby with Down syndrome? I’m nervous because I was told my baby has two echos on his heart and a slight dilated bowl and I heard that they are markers for Down syndrome but I got the testing down my first trimester and it came out fine and then I asked for it again in my 3rd because I was scared and it came back normal again , but I’m still terrified !!!? Please help ugh