Yes, whatismyip.org will give you the IP address of your modem. I can ping your address, which means your modem is responding. If BOTH Port Forwarding is set up correctly, and your ISP does not block the traffic, then when you go to
http://70.231.60.185 it should send you to the webcam. That's not happening.
Here is what to try:
1) Make sure Port Forwarding is properly set up. That can be somewhat complicated, but your manual should explain. Unfortunately, I don't have your router so I can't walk through it. Basically you need to set it so that port 80 forwards to the local address of the webcam. You should set the address of the webcam manually, which you seem to have done since it works at home. Also make sure the webcam is using port 80. That would be in the webcam's configuration. Note that you will be able to use the webcam on your home network whether or not this is set up correctly! You may need to reboot your router when you change this configuration.
2) If that fails, then try changing the port number the webcam uses, in the webcam configuration. Then, change or add port forwarding for that new port. I suggest port 8080, but any will do. Now, when you try to access your webcam from outside, you would use
http://70.231.60.185:8080 or whatever # you specify. Try a few different numbers to be sure.
3) If that fails, you can turn on Remote Administration (most routers have this), which would allow someone (like me) to access your router configuration from outside and check your setup.
4) If all that fails, your DSL is likely screwing you. You can either pay them to give you a home server account (extra $10/month usually, sometimes more), or you can use your webcam's feature of posting its images to a remote server. That will circumvent you having to access your webcam directly at all.