Perhaps your domain name is tied to your wp.com account?
Bluehost should also have a one-click install for the wordpress.ORG self hosted version. They can get you setup with a wp install on their site.
These forums were CLOSED to new posts on November 19th, 2012. New forums are here: http://www.studiopress.com/forums/
and you will need to SIGN UP AGAIN.
If you need assitance with setting up your theme, go to http://my.studiopress.com/
and read the SETUP links or the TUTORIALS link on the side tab.
If you need Account Assistance
, file a help desk ticket at the same location.