I took the index of your words, transformed the selection to binary, included a few zeros, calculated the sha256 digest, took the main A part of the hexadecimal to transform it to binary, extra three zeros for the 8 digits with the binary and received 00000010011 which interprets to 19 https://socialfactories.com/story4366074/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool