Thickened Nuchal Fold 21 week II Ultrasound- short femur length too?

We went in for our 21 week ultrasound and our little guy would not hold still the whole time. The tech didn't see the 4 chambers of the heart (we will have an ultrasound at the high risk office on Monday)- and she noted that he had shortened femurs and a thickened nuchal fold (7.4mm). Everything I've read says measuring the Nuchal fold past 14 weeks is not a reliable indicator for down syndrome, and since my husband is thick necked and short (I am short too), it could just be our genetics, right? I am 21 and we have a 1 year old child with no genetic issues. I sent for the triple screening (genetic test) but I refuse to do an amnio because we would keep him either way.. Does anyone know what the odds are with these results? I don't want to think he for sure doesn't have DS, but I also don't want to sit on the fence for the rest of this pregnancy. Our ultrasound tech was also kind of absent minded and having a lot of trouble, could measurements be effected by her?