I have been playing Fallout 3 GOTY edition on my PC. I have been tromping around the Wasteland killing everything and just noticed my XP points are not accumulating. They are at MAX! I'm stuck at Level 20! Any solutions and explanations would be appreciated.

Is the GOTY retail disk or Steam version.

In the game launcher you should have an option for data files or something like that. Make sure that the DLC's are listed there and they have a check mark on them.

Also FOMM (Fallout Mod Manager) and NMM (Nexus Mod Manager) have options to check to see if the DLC's are there and you can set them active there.