DDCC from July 2010 - sorry, I couldn't help but notice your thread and comment. I had a traumatic birth with dd1 and it took me a long time to write it too. I did it in many stages over time. I had a draft that I ended up changing and editing a few times. At a certain point I just had to let myself be brutally honest and transcribe all the crappy, scary feelings (pain, fear, shame). Then I put it away for awhile. Now, looking back 5 yrs later, I wish I could go back and hug that old self of mine because you know what, dang it, that was a difficult birth!!!
You could go back there in bits and pieces as it's safe for you. This may not be the right time to get back into those teary spots or traumatic memories. How are you doing WRT trauma, btw? Do you have any symptoms of PTSD like flashbacks/daymares or nightmares about the birth?
When you talk to your dh about the birth and start remembering things and get teary... that's okay, you know? Maybe you need to go there and get stuff out writing a version for yourself as part of your processing. The version you end up sharing with your child when they're older may be a very different one.
One of the things that finally gave me peace with dd1's experience is all the reflection I did, and putting it into context with personal growth and development I went through as a mother and a person to get there.
Sorry I'm rambling, not sure if anything I said was helpful, just getting some thoughts out there in case something is helpful to you.
Be gentle with yourself.