I also have two angel babies. I just had my "rainbow" baby last month! Rainbow babies (babies born after loss) have an extra layer of specialness. :)
There are a couple of forums you might enjoy. http://www.mothering.com/community/f/156/pregnancy-after-birth-loss is for moms pregnant after loss and then there are Due Date Clubs where you can get to know other moms who are due the same month as you. These due date clubs are AWESOME!!!! I LOVED mine.
Welcome! I'm sorry for your losses, but huge congratulations on your 3rd pregnancy! I second the Due Date Clubs. I was in the July, 2009 one and all the mamas there were amazing and supportive. I'm even still friends with some of them!
Here's to a happy and healthy pregnancy!