Core blog module only shows two blog entries?
Can you reproduce this behavior using your module set, but with fresh install and blog posts entered manually / generated with devel generate? If not, it's migration failure and your best bet is to export content from old site (you have backup, don't you) and import it to the new one, without Drupal's built in migration tool.

If this happen with fresh setup too, try changing theme to one of the supplied core themes. If it works, then, it means you have a bug in your templates. If it's not, I need to get more info to further expand my answer.