Perhaps someone has a better tool, but this is my recommendation based on what I know:
In your Google sitemap account you can find words that your site is ranking well for.
Then plug these into this SEO Chat tool: (
www.seochat.com/seo-tools/search-engine-keyword-position/ ) one at a time and find your rank.
Or use a paid service like submitnet.net to check your position for all entered keywords in one report.