Mooncalf - so sorry that you've had such worrying results. I just read back through the last few posts and you had your scan yesterday, the nuchal fold was 1.8 and presumably they took bloods? It just seems incredibly quick to get blood test results back (I think mine took about a week when I had mine done in last pregnancy, although I could be wrong).
In my last pregnancy, I was told I was high risk after the 12 week screening. It wasn't super high risk (around 1:128 I think), but presented to me as a bad news situation and also one in which it was a given I would have invasive testing done. We were really unsure what to do, but I did get an appt with a consultant at the fetal medicine unit in a nearby city (it was our nearest specialist centre) with a possible view to doing the tests, but more with a view to seeking advice and getting the results clarified. We spoke at length with a consultant and she also did another scan. We talked about the risks of testing and what we would do regarding the test results. After scanning, she told us a cvs wasn't the safest option due to the placenta being at the back and advised we return for the amnio window in a couple of weeks. We did that, and saw a different consultant, another scan, and more discussion about how the baby looked and so on. He also spoke to us about the risks of having the test done (which are not as bad as they are usually quoted to be). At no point was I under any pressure to get the test done, and up until the needle went in, he reassured me I could change my mind at any point, which was really helpful.
Sorry for long story, but my point is that I think it could be useful to get the ball rolling regarding testing, if only to see a consultant to have a long chat about things, especially which factors are indicating a high risk result. Harmony testing will give you a clearer idea, but I'm not sure how much information relating to your specific situation they will be able to give you. Meanwhile, hang on in there, and if you get the chance, please do try to get hold of ARC tomorrow as they were fantastic when I rang them. Meanwhile thinking of you and hope you get some answers soon.
By the way, a friend of mine was given a 1:5 result and her baby was absolutely fine.