I am in the EXACT same boat. I was doing good, October and most of November went by without a hitch, then I got to Thanksgiving. I've felt lost ever since. I think it's a combination of everything you've mentioned - Christmas, holiday baby announcements, your due date etc. For me, it's definitely the holiday and the baby announcements. I've shut myself off from the world and haven't made any plans to see any friends during the holiday break because I just don't want to deal with it. I want to drown my sorrows in chocolate and block out the world.
I get how you feel - and I'm so sorry you feel like you're going backwards. I wish I had advice, but I, too, just want to go home and cry. *hugs*