A few things... You probably have duplicate content if VBSEO isn't configured right. I have close to 100k pages indexed and the number is going up.
It takes a lot of time for search engines to index unless you are getting lots of traffic. I get lots of traffic.
- Your pages will be penalized if they do not have a mobile version per Google's highly publicized recent update. You can purchase a responsive skin but no mods will work with a responsive skin.
- Set your archive options to 301 Redirect vB's Archive Thread Pages. If you don't you will have duplicate content and will have pages dropped from indexing.
- Turn on Cleanup HTML Code.
- Make sure Replace the 'META DESCRIPTION' Content is set to yes
- Add rel="nofollow" to ALL External URLs set to yes
- Enable Canonical URLs must be set to yes
- Inside your sitemap settings set Include Forum Display Pages to no
- Inside your sitemap settings set Include Show Post Pages to no
- test your site score in google pagespeed. A low score means low priority being indexed and Google shows you in search results less even if you are indexed. https://developers.google.com/speed/pagespeed/insights/