Hi Rach
Just thought I'd be another to give you some reassurance. I was given 1:119 chance of DS with my DD (I'm 29yo so not in higher risk age group and was NOT expecting it) and had the CVS at 12 weeks. All results came back AOK and DD is a bundle of perfect health.

I was opposite to you and had great BT results but high NT measurement at 3.8mm. I had to go on and have an extra U/S at 26 weeks to check for any heart defects but again DD got the all clear.
It is a very scary time and I must say the worst 4 days of my life waiting for the fast results to come through. I really wasn't given a great deal of information by the doctor who gave us the news (VERY POOR BEDSIDE MANNER) and it wasn't until a few hours after the CVS that a work colleague finally put my mind a little more to rest.. The odds really are in your favour but I'd wait and see what your BT and US results combined give you. P.S. The work colleague had a 1:7 chance and had a healthy bubba also.

Good luck and as OceanPrincess said, ask questions if you need to which really helped me as our U/S Doctor gave me no real information at all.