I took the index of your words, converted the quantity to binary, added three zeros, calculated the sha256 digest, took the first A part of the hexadecimal to convert it to binary, added three zeros towards the 8 digits from the binary and received 00000010011 which translates to 19 in https://reallivesocial.com/story4343429/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool