The IP from canyouseeme.org is your public IP address and would be used on the other end to connect to you, you wouldn't need it to configure the port forward. You should only need the internal IP of the computer, which as you stated is 192.168.1.2.
What happens when you put port 1604 in the "Port to Check" box on canyouseeme.org?
I would turn off the firewall on your PC temporarily and see if it works, if it does then you know something in your firewall is blocking it.