I see I can flag my own question and click as off-topic to be able to move it to another site but I only see a few sites in the list:
How would I go about doing this?
Regular users are only able to vote to migrate questions to sites on the pre-defined list. These sites are specifically chosen based on what sorts of off-topic questions are typically asked on Super User. If you need a question migrated to a different SE site not on the list, please flag the post for moderator attention, and state which site you'd like it moved to. Moderators can migrate any question to any Stack Exchange site.