Which is the model of your router? Does it support UPnP? Have you made sure you are not Double NATed?
Can your router show you connection sessions? If you have a D-Link router, check your Status section.
You will need to find a UPnP entry allowing all nets(with *), access to the IP of the camera. Port 554 is to be allowed as well. Being a UPnP device the router is to allow any given port subsequent to port 80.
Still will not recommend modifying to secondary ports to eventually forward them because that will be the point where the camera won't be access in the 'myDlink' site.