Well the question that springs to mind is "Where exactly did you forward those ports to?" I'm going to assume you might have done this incorrectly so forgive me if you do understand how to forward ports correctly.
I'm assuming you're on Windows. From the Windows start menu -> Accessories -> Command prompt. Type Ipconfig and press enter. You'll be given a list of interfaces on your PC. What you need to do is to forward the UDP ports to the IP address of your PC. This will probably be something along the lines of 192.168.x.x but it may even be 10.x.x.x. If the address you forwarded to doesn't match the address of your machine, well it's like telling your post office to forward your mail to a random address, you'll never receive it.