I played ESO in Beta on and ESO account, but didn't purchase the game on release, so have no characters/currency on the account. Later on, I purchased the game on Steam and had always (as far as I can remember - it's been a while) just clicked play from steam and been logged in. On that account I had played quite a few hours, made a lot of progress, and was a member of premium for many months and never spent the crowns.

I quit the game for a long time, but re-downloaded today and went to play, but instead of logging me into the game, it's asking me to link my account to an ESO account to proceed.

If I were to link the accounts, would I lose my characters/crowns/items/etc, or would they override the empty account which just had beta access (no actual purchase history)?

Also, if my memory is wrong and it was never possible to just log in directly from steam without an ESO acount, how could I find out what that account was? I remember some of my character names, but in checking my e-mail addresses, wasn't able to see any with messages regarding ESO aside from the one mentioned above.