Yes, 100%
When I download Bitcoin core and create a new wallet, I am asked for a passphrase containing at least 8 words.
Unfortunately this passphrase is all I have
BR
Gawan
There's a big difference between a passphrase and a 12 word mnemonic seed phrase.
With a 12 word mnemonic seed phrase, it should be possible to recover an HD wallet. A passphrase, however, is used to encrypt a wallet, it's not used to derive your master private key but merely encrypts it. You'll need the original wallet to recover your funds.
So, if you're 100% sure you used bitcoin core, the 12 words are not a mnemonic seed phrase (since bitcoin core doesn't use mnemonic seed phrases), but merely a passphrase used to encrypt your wallet...