If you want total privacy, use Google+. No one will see your posts.
With my book done, I gingerly moved back to Facebook and the first post was my previous blog post about the completion of the draft. In 15 minutes, the Facebook post had 8 likes and 7 comments.
Meanwhile, the Google+ post, with a 7 hour head-start, might as well not exist.
A couple of days later, the Facebook post has something like 30 comments and "likes". The Google+ post has two.
I still have the concerns about the overwhelming stream of information that led me to leave FB, but I was missing the connections that Facebook made possible. Google Plus is a better design, but even the obvious problems are not getting fixed. Meanwhile, Facebook has improved: in particular, they allow you to subscribe only to "Life Events" from some people, for example.