Hi, https://phabricator.wikimedia.org/p/kchapman/ indeed shows that your account is connected via SUL/OAuth to your mediawiki.org account named "Wonderchook". Our Phabricator instance does not store any login credentials itself, so every Phab account must always be "linked" to an external account which is either a SUL/OAuth account, or an LDAP/Gerrit/wikitech.wikimedia.org/developer account, or both. Phab admins cannot edit which external account is linked to a Phab account.
I see two options: Either you create a developer account (anyone can do so) and connect it via https://phabricator.wikimedia.org/settings/panel/external/ , then detach your Wonderchook SUL/OAuth account and attach your WMF account (might require re-login), or you register a separate Phab account for your WMF account.