I should be the happiest woman alive!

Where to start..?
I am getting married in a little over 2 weeks, to the most amazing man in the world. David & I have been through so much in the short 2 years we have been together and knowing that I am marrying this man gives me indescribable feelings.
We just found out that we are pregnant! I have yet to go to the doctor, but we will get there. I am happy, so happy, but Im worried, very worried. As most of you know we have 3 little girls already, and David is leaving for Afghanistan verryyy soon. I pray every day that he will be able to come home for the birth, but even so he will have to leave again, and return when the baby is almost 6 months old. Thats depressing. I have some of the greatest friends here and I have no doubt they will go above and beyond to help me out while David is gone, because they do it while he is home. I just havnt let all of this hit home yet I guess.
We bought a new car, with 3 rows. =)) & its MOMMYS CAR!
Yet somehow, I am not excited, well lets say, I dont FEEL excited about anything. I am just...Bluh. Maybe it all hasnt sank in, maybe its hormones, I dont know. I wish I did. I know I am happy with everything, except him leaving. I am just not excited, not as much as I feel I should be I guess. Maybe it doesnt feel real yet?
When will it?
Maybe it is all just too bittersweet? Yes, we are getting married, but then he leaves for a year. Yes we are having a baby, but he is going to miss so much. I am horrible, absolutely horrible at finding the positives in life. To most people my life seems so perfect. I have an amazing man to call mine, 3 beautiful healthy kids who dont want for a thing in life, and one more on the way, a great life.....Why am I the only one who cant see just that?