You don't need to forward a port for LAN hosting. You simply have not been using the correct IP for the other players to connect to.
Go to your Command Prompt and type in "ipconfig", then press enter. This will give you the IP address that other computers on the LAN need to connect to you. Here's an example:
I have circled in red my local IP address. This is what all the other computers on my LAN at home know as my computer. So what you're looking for is the IP Address listed under Local Ethernet adapter Local Area Connection.