When I took the test last year, the narrative was submitted with the application for the written test. If I had it to do over again, I'd have probably gone into more detail than I did. Judging by what I've read in your posts, I'd say you have a background that will be interesting to the review panel, & you express yourself well. Respond to the questionnaire, & tell them who you are & where you've been.
The big challenge seems to be the Oral Assessment. The explanatory materials on the DoS website explain the process well. There are three main components: a role-playing exercise with a group of applicants, a written exercise where you address a management problem, and a structured interview with two FSOs. The DoS website explains the process as well as I could ask for.
I'm waiting for the security clearance before the next round before an evaluation panel.
Best wishes.