Relax......enjoy your pregnancy. Everything will work out just fine. I've done it 5 times and things always seem to fall in place. You got alot of good advice on the main things you'll need and also about waiting until after your showers to see if there's anything that you absolutely need. Most will be given to you at your showers and then you will just have to add things slowly.
Once you master changing a diaper, which won't take long, you'll be able to do it with your eyes closed