og-tag errors in Facebook debugger, image thumbnail not showing

I have been having troubles with posting to Facebook for months now (even before the latest WordPress update or two). My image thumbnail and excerpt don’t show up; then I go on WordPress forums to remind myself of all the things I can try doing to fix it; I try all the things I know how to do; then I empty my caches and run it through the debugger every time; sometimes I can eventually get the post to work, and sometimes I can’t. I’m never sure quite what it is that has worked.
I’m running Yoast SEO and I have done my best to eliminate any other plugins that could be duplicating my tags. My latest post I have not been able to fix: https://itsdilovely.com/2015/09/15/calm/. I haven’t even bothered to post it to Facebook. I would really really love some help on this.