Your account is defined by email. If you have signed up with regular account on email A and then sign in with Google using email B, you've signed in into other account. If you want to use both regular and Google sign up, you must have the same email.

Currently you have 2 accounts. If you are currently signed in with Google, you can save your progress in cloud for this account, sign out, reset your progress, sign in with regular account and load its progress from cloud. Unfortunately it is not possible to have the same progress on both accounts because some players were abusing this feature and shared their progress through fake accounts to other players.

If you want to change an email for your regular account to be able to sign in with google, please contact [email protected]