Sadly we aren't taking username change requests right now. =( The last batch was in January and are usually done twice a year. Admins are currently working on a way to change usernames yourself though but you'll have to be a little patient for that since it'll be a bit before the new system is ready for release. Once it's available people should be able to change names quickly without help of a staff member straight through their control panel. We usually do minor name changes anyway, like fixing capitalization or a spelling error, but not bigger requests since then others will start asking too.
In the meantime you're welcome to make a new account if you want a new name. You don't have much to lose out on anyway, since you only have a few posts!