Hi sweetie. (((((HUG))))) first (I don't care if it's un-MN, you need it.)
I had a similar situation to you although I was a bit older when I was pregnant with Jackbaby (38). We had a nuchal translucency scan which was completely fine but then had the quad screen blood test which gave a dodgy result so had to have an amnio to know for sure. I was 16-17 weeks at the time.
The actual procedure isn't too bad - I won't tell you it's nothing, because if you're anxious and upset you feel everything more. You'll be lying on your back, and there will be a sonographer who'll be scanning you so the doctor knows where to insert the needle. He or she will swab your belly, and then insert the needle so it goes to a pool of fluid. When the needle went in, I felt a "pinch" in my skin, not really like a needle jab, and then felt a sort of "pop" as the needle went all the way through. It was a bit disconcerting but objectively, not that bad. My belly muscles sort of cramped around the needle, but I can't say it was really painful. What was worse for me was that I was in such an emotional state that I was almost hyperventilating - so if you can keep reasonably calm, it's better for you. The entire procedure took probably two or three minutes, it really is very fast - but it's a long two or three minutes IYKWIM.
Afterwards, you'll need to rest for at least one full day. I didn't cramp at all, but I know some women do. I was told to take extra Calcium/Magnesium after to help my uterus relax, so I did.
Our specialist took pity on my nearly hysterical state and sent the sample off for the FISH test (fluorescent in-situ hybridization) which tests chromosomes 13, 18 and 21 - the Big Uglies in terms of problems. You can have results as quickly as 24 hours, but 48 hours is more usual. Ask for that!! Waiting ten days to have the entire karyotype analyzed would have done me in, I was bad enough over those 48 hours.
Let us know the date of your amnio and we'll hold your hand. You'll be fine.
Lots of love and more (((((((HUGS))))))))