Since you said that you would not terminate, ask yourself if in the small chance there was a problem, would you rather know now or at the time of delivery?
I am not sure what 16 week u/s u are referring too, I didnt have another one until 20 weeks. At 20 weeks they can see malformations better than at 12, but they do not look at the nuchal fold then.
They do a blood test called the triple screen at 16 weeks (but again you can opt not to have it) and if they get abnormal results with the blood they will send you for a scan.
Everyone feels differently, I think I would want to know early to get resources in place and figure things out. I had nuchals done with both of my pregnancies
congrats on the pregnancy!!!