M.F.
Dear T.,
I also lost a twin at about 8 weeks and when I went in to get that test they told me the results could be skewed. The doctor said it had a lot to do with the amount of hormones still present in your system. Like you, I was a nervous reck and wished that I hadn't had the test done to begin with. In the end my ended up fine, but they really did warn me the chances of a false positive were very high. I would do the amnio if it will put your mind at peace. If you are young though, you might want to weigh the risk vs benefits.
Hope this helps.
m