Sleepstarved, first of all congratulations on your pg.
Secondly, my goodness, what a huge amount you have had to take in! I know from all your previous threads that you have had worries and doubt about dd for a long time, but it must still have come as a huge shock to get a diagnosis.
The positives are that you already have so much support in place, and you are already on the huge learning curve that is fighting for support in the world of sn. Dd is lucky to have a mum who is on the ball, and fighting for her.
Ds is our 3rd child, and I am so glad that he has his sisters, they adore each other, and are probably his best therapists. Now he is walking, he follows them around the house constantly, and he is good for them, they look out for him and take the time to play with him, and help him up when he falls,and i know that things will be more difficult for them as they grow up, but I am so glad they have got each other. I have a 1 year gap between dd1 and 2, and it was pretty hard (especially as dd1 wasn't walking when i had dd2, and she didn't walk until 21 months!) but not half as bad as everyone said it would be, and they are now so close, they really are best friends (obviously there are times when they have to be put in seperate rooms before they kill each other!)
It is very tough to not be able to enjoy your pregnancy, but you just have to be kind to yourself, and take it easy, counselling does sound like it might be a good idea - a place to offload (of course you always have mumsnet sn boards as well). I found pregnancy hell all 3 times, but it kind of made the newborn days feel easier!
Your dd sounds as though she is doing so well, and you are doing so well too.There I have written an essay too!! Look after yourself.