If you go into your user account there is an option to change the account name. It may not actually change the folder names, but you will have a new user name. It has a shield, which means it needs admin approval. The account is an admin account, right?
Perhaps the best way would be to set up the user you want and move stuff over, although I have not tried that.
I thought you said you had a normal account with the name you wanted. I suppose you deleted that one?