Three months ago I published my small personal website (~10 pages), submitted the URL to Google, and a few days later Googlebot showed up. Over the course of the last couple of weeks, Googlebot visits my website approximately twice a week and crawls maybe every other page.
Ever since Googlebot first crawled my website, whenever I run a search for site:example.com
Google returns only my homepage. (Interestingly, so does Bing, so maybe the problem isn't specific to Google.)
I built the website with CodeIgniter mainly to familiarize myself with it. It's really simple, only a couple of pages about me and my projects. I am not using any black-hat SEO techniques, JavaScript, or anything like that.
What could be possible reasons why Googlebot would crawl my pages but not index them?
EDIT: I do have a Webmaster Tools account. There are no crawl errors, internal links are listed, but listed keywords come only from my homepage.