Hi hon, I was given a 1-50 risk for DS and declined a CVS or Amnio... so had the same agonising wait for a detailed scan at 20 weeks...
We had a fantastic sonographer and she was very patient and spent a lot of time showing us various areas they look at for soft markers - length of femur, bowels, heart, brain.. we found it very reassuring as no soft markers were present (even though it doesnt rule DS out completely). I found having to make a decision about further testing the most stressful part of the whole situation (had to be prescribed beta blockers because I was getting really bad stress related heart palpatations!) and of course the wait from 13 weeks until the detailed scan at 20 weeks was by far the worst part of my pregnancy..
My little girl is due next weekend and although it is slighlty at the back of my mind, I am now very confident she is going to be fine... you have to try and keep a positive frame of mind, even though it is really difficult especially as you have only just had the news...
I really understand what you are going through - if you want to chat or ask anything else, feel free to pm me... Best of luck with it all xx