An amnio should tell u if the baby will have ds or not. A friend of mine tested positive for ds and then did an amnio and everything was just fine. Don't stress everything will be fine.
Well, from what I understand, the tests do not confirm DS, they just predict the likelihood that the baby might have DS. Ask which tests predicted DS and what the percentage of the possibility of DS. I had a cousin who had a test that predicted DS and her baby was born perfectly fine. Either way, your baby is a gift from God, a person in his or her own way.
Is the Dr going to run more tests such as amniocentesis? That should prove it negative. Don't let the fear get in your head. Stay strong.