I believe you are fairly young so I might opt for a NT and then an amnio if you want more of a definitive answer. The Drs in my area(Boston) were not too big on doing a cvs at all. They thought I was crazy to consider it if there weren't any indicators there could be a problem. It is stressful to wait 4-5 weeks more but the risks with amnio are so much better. I was even worried durimg the amnio when I saw the needle coming sort of close to my baby's bobbing head as she slept. Then I got nervous about making sure the pin hole sealed up properly and that there wouldn't be any contractions after the amnio etc.
I think what has changed my plans with all of this is the identical twins situation, I just feel I need to know as soon as possible now but maybe I am being hasty, I am going to try to think about it some more over the next week and I pray that when I meet the peri I will feel confident with whatever I decide. I was just wondering if there were certain risk factors that may predispose someone to doing worse with the procedures. I am sure the peri can tell me if so. Thanks and good luck with your baby.