Which exact version of Eu3 did you buy? The old base game? Complete? Chronicles? Each has their own entry in MyGames.
The only tricky bit is if you buy Chronicles from Steam, for some reason they give you three codes (Complete, HttT, DW) rather than one Chronicles code. I see you've registered DW, so you probably have that - so just register the other two in those sections.
The only tricky bit is if you buy Chronicles from Steam, for some reason they give you three codes (Complete, HttT, DW) rather than one Chronicles code. I see you've registered DW, so you probably have that - so just register the other two in those sections.