Given I understand what "sees" means here (what does whatismyip.com say it is??) tcp_outgoing_address is used for the actual network level connection, which is always an address on the squid server itself otherwise the basic connectivity is impossible. it will see your workstation IP though as Squid will (and should) add an X-Forwarded-For header to the request on the way through. You can tune this behaviour if you want to -
http://www.squid-cache.org/Doc/config/forwarded_for/ just note that you've mixed up the management and use of IP address information at different levels of the stack. tcp is OSI Layer 4, and the XFF header information is nice and fluffy up at layer 7 so are technically totally unrelated, despite both being about IP addressing.