A problem with linked Steam account

I recently decided to play some swtor after several years. Back then I first played the game directly through the launcher, then I came back some time later and played with Steam. I guess I must have linked some account to the Steam account but I am not sure if it was my old one or if I made a new one. It is certain that I played on Steam since I have some achievements there.

So today I downloaded the game via Steam. Naturally I didn't remember what my Display Name was, so I searched through my emails and found the account (the original one). Entered the name and password but the launcher says "We can't log you in, Please double-check you're using the Steam account you usually play on and try again."

When I log in through my browser to swtor.com I can see my account with my old characters still but the account says it is not linked to any Steam account.

Is there a way to find out which SWTOR account is linked to my Steam? I don't really care which account works, I just want to be able to access the game.

Also a weird thing: my Steam says I have around 15 hours in the game but I have 26 unlocked achievements including achievements for story missions for Jedi Knight (8 planets and some chapters), Sith Warrior, Jedi Consular and Agent. This suggests that I actually must have linked my original old account to Steam since I doubt this amount of content could be played in under 15 hours.