I am out of my league

Geesh, learning curves can be both exciting and anxiety provoking.
So, I used the term platform when I should have said target audience. Specifically, my target audience could be recovering junkies, people who have been silenced, women who've been abused, parents of recovering children, or those who need someone to listen to their stories. That's the decision I need to make before developing a marketing strategy. As worded, it seems to broad to me? I'm concerned that if I go with the drug abuse strategy, my book will be minimized to a recovery book, but there's a large population of recovering people and I'm active within the community.
As far as a release, I did check into that before I began writing. The information I used to recall my memories was gathered from my observations of a specific person, but the identifying marks are typical within the general population. So, I think I'm okay there.
Do most authors set up a fan page before they even know which direction their book is going?
I know how difficult it is to reply to questions with little knowledge of what's gone before and want to thank you both for taking the time to help me sort through this stuff.
Where are you both with your projects? I'll see if I can find some of your posts and read something you're working on. There's so much to learn

Silly me thought all I had to do was write a book