Only other force sensitives can scan others for sensitivity to the force. If you plan to remain a freelancer than you will need to find a FS person and ask them to scan you. Many of the bigger factions set up scheduled tests for force sensitivity for their members.
If you get tested at lvl1 and your not FS then your chances go up every 5lvls. So your chance goes up when you hit lvl 6 then again at lvl 11 and so on.