i had one at 15wks due to 1/82 risk of ds from my b/t. bub showed no signs and the nt was good but my blood results made for the high risk. it was painful for me, and had to have the needle go through twice as dd tried to grab it the first time so she withdrew and had another go a couple of minutes later. i got the fast results within 24hrs and they were clear, as were the full results 3 weeks later. The only advice is the same as above, find someone experienced to do it, take someone with you and rest for a few days after. hugs to you, its an incredibly hard decision, ive got my fingers crossed for you