I'm freaking out ..... please help

I had a blood test done it was just a screening and the doc said I have a risk this baby can have Down syndrome but the thing was he also said sine I was 14 weeks when I had the blood test the baby wasn't that big producing whatever fluid it is so it was low anyways he also said 98 percent of the time eveything turns out good once blood work comes back does any one know anything about this 
I'm sorry about punctuation I'm just freaking out so much right now