Hi Iam,
Yes, you are on the right track. I have written a two part post entitled, "What do you mean I have three brains?!" at ramblingsontrauma.com. The posts help to explain why the reactions you have are not your "fault" based on the biology of the brain and its development. Another part of the scenario is the Reactivity Map. I haven't finished that post yet, still working on how to get the visual into the post correctly. Essentially it maps out how you respond to a stimulus automatically and react in a predictable way based on the templates you have in your brain for what that stimulus means. PTSD has a funny way of really messing up the templates and corresponding actions.
Best,
Mark