If you open your phone, and take out the battery, you will see a label underneath the battery. On that label, you will see the code. On mine, the code is just above the FCC ID.
There are applications out there that will allow you to change the code on the phone. (Not warez...but actual programs that are legit.) If you change the code to something that matches a code for which an update is available, you should be good to go. I believe there is a thread on this somewhere in this forum.
I believe your hypothesis is accurate. The reason you are not seeing an update is because the firmware is not yet available for your phone's code. For whatever reason, this happens with APAC versions of Nokia handsets; it is the same for the E61, which still doesn't have the latest firmware version available for APAC versions.
Joel