I'm now thinking maybe just enter the Trezor twelve word seed into Mycelium to try and gain access and then repopulate a new Trezor twelve word seed, right? If I did it the first time, I should be able to generate a new one.
Try to check it on trezor suit instead since you mentioned that you imported the samourai wallet seed to your trezor which doesn't work earlier and now you imported back your trezor seed to trezor.
If it does not work, i could only think the worst — that you backup the wrong seed, i hope im wrong though.
Also, when attempting to import from trezor to mycelium it asked if there was a passphrase and gave the option to skip if there was none. I dont have one written down so I'm thinking there isn't an associated passphrase with the twelve word seed. Should there be?
Yes, you can skip that if you don't have added a passphrase to your 12 word seed to make it 13. It's a feature to make it safer and hard to guess.