I'm now trying to understand whether my 12 word seed was generated by a post 2.0 version of Electrum or some other wallet type.
Does anyone have an idea what wallet type that had the same look and feel as Electrum existed in or before 2011?
There has to be an answer to this mystery. Let's solve it.
Even if it could be a lot of work the best would be to use all different wallets that were available in that time and try to put in the seed words that you have. You say that the only time you touched your bitcoin was in 2016, so there is a chance that you send them away at this time so if you check your wallets and they display the amount 0 you should also check if you see transactions in 2016 (or any other time if your wallet was compromised).