Don't worry too much as MadB said. There's nothing you can do about thyroid levels, they are what they are unless you take medication. However, I'd call them back and ask if you can see them after the bloods but not wait for the NT scan as that is still a bit in the future (plus, I don't see how the NT scan matters whereas I'm pretty sure the additional blood tests are necessary and shouldn't take long). Tell them you would be happy to come back after the NT test as well. I'm a pretty pushy person when it comes to doctors.