Down syndrome marker

Mikayla

So as a FTM I know I’m overly worried but I can’t help it. So my anatomy scan was today I’m 18w 6d. They said everything looks good but they noticed that the baby has a calcium deposit on her heart, which is a marker for Down syndrome. But they said since I got my genetic testing done (at 11 weeks) and it came back negative that there’s nothing to worry about. Just need some reassurance please.