First trimester screening low proteins !

Jen
Hello everyone I just had my first trimester screen for my second child's im age 35 now the NH test came back perfect but they told me I'm at a elevated risk for downs since all of my protein levels were low I was only in the 2 percentile for HCG. Baby is measuring perfect and growing but needless to say we are scared to death I took the maternity 21 blood test and should find out in 10 days. Has anyone else experience this ? And hopefully the test will come back negative but what else do I have to worry about with these crazy low protein levels ? Any information is much appreciated thanks