I have had two amnios done...
The first was with my daughter when I was 25 and bloods came back as high risk 1:250 (I think) the test was done, a little uncomfortable but nothing painful and I waited for 2 weeks for the results and all was fine.
With this pregnancy we had the nuchal fold test done which was normal at 1.6mm and the bloods and all was normal and I was 1:630 but we decided to have the amnio done all the same. The test didn't hurt at all, I hardly felt a thing. The results came back fine.
However, a friend told me a story the other day... that her friend had the nuchal fold test done and all the tests came back fine, no flags or markers for Downs. She had the baby and it was severely handicapped to the point of no much of a life at all. Its such a sad story. They were in so much shock they could not keep the baby in the end and she was put in care. I don't want to scare you as this scenario hardly ever happens where the case is so severe but it worried me into having an amnio and proves it does happen. I asked the doctors lots of questions and they said (and midwife as well) that the nuchal fold test results are only EVER 75% correct. Therefore, I don't think they should carry out this test personally. A lot of people are led to believe its more accurate than it actually is.
All in all... I was frantic when I got my results with my first as I was high risk but it actually only means you are slightly out of the low risk category, there is no inbetween category. This can also be caused by your hormone level being high which was my case. More often than not those in the high risk category that have amnios their results come back as fine so don't worry.
In answer to you question about your results, I think she has called you back with regards to the nuchal fold measurement (I dont know what the rest of the measurements that you list are, sorry) Ours was 1.6mm, I did ask at the time what was the maximum and she said that it was in the average category at 12 weeks if the nuchal fold wasn't more than 2.1mm. Maybe the doctor just wants to take some more detailed measurements? I don't know and would not like to guess as i'm not a doctor.
Good Luck with everything x