Hi Ben, it seems like you've got a pretty solid strategy in place. I appreciate that social media can be a tricky platform to negotiate when you're working in a sensitive industry like this, and maybe you'll find that some networks simply don't work, while others do.
One thing that I might suggest is to spend some time deciding on the niche you want to reach through social media. Connecting with potential patients in this way might be difficult for the reasons you state above (privacy, reluctance to share/like/discuss openly). Establishing your reputation and increasing your visibility among the counselling community could be achieved by joining Twitter conversations, connecting on LinkedIn, commenting on blogs, answering questions and, once you've built a following, sharing your own content.
Perhaps patients are better reached through SEO-promoted posts rather than social media promoted posts (link building, solid guest posts etc.). Having said that, there are probably lots of ways to utilise social media - e.g. awareness generating campaigns, conducting research and sharing interesting statistics and findings etc.
Good luck!