i dont think there is a good soulution for you.
if its out there, somebody will find it.
you could host your own wordpress instance independent of WordPress.com.
and you could add a robots.txt to tell google to not scan your content, or even completly block the user agents of known search engines.
but blocking search engines is rather counterproductive if you want readers to find your blog.
and even then more nefarious crawlers might ignore the robots.txt and spoof their user agent to find you.
into depression i guess