MommyRamblings - Ask at WordPress.com to see if there's a limit. There isn't one I know of, but most folks here are .org (i.e. self hosted) gurus. I kinda-sorta use my .com blog.
Make sure you specify if you're trying to export from wp.com, save it to your desktop and THEN upload to your self hosted or not.
As for bluehost, they're being stupid. The problem is, YES, your install of WP has a 10 meg limit. They're right there. But they're being daft because the limit is SET by them in the php.ini file for the server.
Wanna know how I know? They have a freakin' document on it: https://my.bluehost.com/cgi/help/110
(Also if you can do us a solid and not make so many posts in a short time ;) We're volunteers and posting 3 or 4 times in an hour begging for help ... well you're a mommy, it's like that toddler who really wants a cookie when you're on the phone with the gas company ;) )