I took the index from the words, converted the quantity to binary, extra 3 zeros, calculated the sha256 digest, took the first part of the hexadecimal to transform it to binary, included three zeros on the 8 digits of your binary and received 00000010011 which translates to 19 in decimal. https://doctorbookmark.com/story19523311/a-review-of-bip39-passphrase