I agree with those who are encouraging you to try to not be upset with this one test and the comments given to you, although I realize that that can be much easier said than done.
If you're of the belief system that you will carry this baby to term regardless of any test results, then there is no point to exposing the baby to any more ultrasound, because there are only 1 or 2 conditions which can be addressed before birth anyway. In addition there is a school of thought that ultrasound exposure does carry its share of risks.
If you are interested in what those potential risks might be, there are several articles on this page which deal with that question....
http://home.mindspring.com/~djsnjones/id7.html
Also, if you are concerned about the bsby's size being behind schedule, you can try this diet to help him/her catch up to the size s/he is supposed to be...
http://home.mindspring.com/~djsnjones/id64.html
And here is a story about a mother who was able to help her baby to catch up with her growth, after a whole month of no apparent growth at all...
http://home.mindspring.com/~djsnjones/id22.html
And here is a good book on how early prenatal testing can affect the mother mentally and emotionally. You can probably find it in your local library, or ask them to get it for you through inter-library loan...
http://www.google.com/products/catalog?q=0670808415&c...
May you have peace,
J.