Help. Down Syndrome?

Hi, I went into the doctor today for my 20 week sono, only to be told that they think there is a chance of DS. When he said this, he was saying this because of how her nose is and how her chin is. I has some asian that runs into me as well as a decent amount of native as well. They asked me if I was sure on my due date and I told them I wasn't so sure because of how weird my period was before I got a positive test back. So they say there might be a chance of being a week or so off. If that was the situation, is my baby okay? Do you think that she has it?