Advice an support

I’m a mother of a two year old boy he sure is a handful. I’m currently pregnant have about 4-5 weeks to go. When I was about 21 weeks pregnant I found out that my boy may have something wrong with him. My doctor suggested that I go see an ultrasound specialist for more information. Just like my doctor did the ultrasound specialist found a space between the back of the head and the spine. He said it was a bitlarger in size then normal, but was not sure what it was caused by. The ultrasound tech said the head portion was normal size. What he did find is that my baby does have a two vessel cord instead of three. The feet are fine but on the pinkie there is only two bones instead of three like there should be, and on the face he said the nose bone should be a little smaller then normal. So far since I have not done the amniocentesis test we are not 100% sure if he will have any down syndrome. The ultrasound tech said when looking at the brain that he still sees possibilities of Dandy Walker Variant. Hes suggests after baby is born that he have a cat scan and blood work done. Right now im 35 weeks and 1 day along. I have once a week dr and ultra sound visits. I had an ultrasound visit yesterday. The tech said that a month ago 02/02/2010 at my visit he weighed in at about 3 1/2lbs and now hes only weighing in at about 4 1/2lbs they would like to see him on the closer end to 5lbs. Also on his growth chart he isnt seeming to go up like they would like to see him he is actually decreasing coming down. If after not next weeks visit but the week after which would be at the two week visit. If he hasn’t been going up on his growth chart or gaining much weight. They are going to suggest to get baby out. I’m hoping everything will work out. I’m thinking as positive as I can. I’m just a bit nervous since i haven’t been around a child of my own or around a person a lot tat has any kinds of dandy walker or down syndrome. I have friends with different kinds of down syndromes they are great people and I love them just as if they were a “normal” regular non down syndrome person. I just don’t know how to react to whatever he is going to have wrong with him. If there is anyone that can help me prepare myself a little better since I have less then a month to go that would be great. Looking forward to talking with anyone that has some more information on dandy walker or down syndrome, an that can be of help about support groups an that sort of thing. Thanks so much god bless all of you Emily.