Multiple Categories After Importing

I’ve had a wordpress.com site for several months now (www.lifeinasack.wordpress.com) and just switched it over to a self-hosted solution (www.lifeinasack.net).

However, during the import/export process, all of my categories became separated, as in I would have 10 posts in “Central America” but now I have 10 central america categories. Does anyone know what is going on here and if there’s a way to fix it?

Thanks!