I am sorry for the inconvenience. I have checked this, but unfortunately, I cannot change your email address manually or see the steam key to your purchase. Only itch themselves can do that.
It looks like you have downloaded the DRM-free version from itch. Do you still have access to the download page of the game? That is where you can claim the Steam key.
I would recommend just playing the game via the files you downloaded until you receive the key. Savegames are compatible with the Steam version, so you could seemlessly continue. I will reach out to itch support myself as well, and if they can't get it resolved, I will send you a new key.