I am really reluctant to post here, as it is your decision and only you can know all the factors, such as how would you feel if you didn't have it and something was wrong and how would you feel if you did and mc. So, this is my opinion only, and based on my own level of comfort with risk (not great TBH). Personally, with the NT risks you were given, I wouldn't be having further testing, as the risk of mc is greater than the risk of abnormality. But, as I have mentioned, I am risk averse. With both DSs I had great NT results (something like 1:2026 for Jack and 1:3000 for Tom), and this allowed me to feel relaxed for the rest of the pg. So I would not have risked mc. BUT clearly your great NT result (and it is a great result) has not been enough to make you feel relaxed, and you do need to consider that too. Therefore your decision might well be different to mine.

I am sure this post hasn't helped you at all but I do hope that you can find some peace and enjoy the rest of your pg.