I remember being in your shoes - not fun! While it's great to have all this technology, it certainly adds stress to pregnancy. I hate the nuchal translucency test and others like it because they only give you statistics/odds, not really real information (at least that's how I feel). Especially when you are over 35 (they adjust the statistical calculations according to age, so being older automatically puts you in higher risk odds). I even posted looking for opinions about amnio (http://www.mamapedia.com/questions/4857232997042225153)
I am not a fan of invasive testing, so I decided to see what my results of the quad screen and further ultrasounds were before deciding to do amnio. The only issue with that is then you are waiting to do amnio later in the pregnancy. My quad results ended up being good and ultrasounds were fine. I discussed the results with an amnio specialist and he even recommended against amnio. My daughter was born healthy (I was 36 at the time).
That being said, you need to do what will give YOU peace of mind and find what you are most comfortable with (not that you'll ever be 100% comfortable!). My gut told me that my baby was fine, so I focused on that and tried to tune out the anxiety. I learned a wise statement to tell yourself when you are starting to imagine all the things that could go wrong - just stop your thought process and say to your self "That is a story that doesn't have to happen." It has worked wonders for me.
Wishing you all the best!