High risk for trisonomy 18 and 13

Em

At 13 weeks my fetal fraction is still only 1%. I took the panaroama rest twice and got inconclusive results twice because my fetal fraction was only 1. I'm 13w2d and have been referred to a MFM specialist but will be past 14 weeks for the US screen to measure my babys neck and I'm panicking. My doctor says they dont do it the high risk doctor does but I cant get into get it done until it's too late. What do I do