I took the index of your words, converted the selection to binary, added a few zeros, calculated the sha256 digest, took the main part of the hexadecimal to transform it to binary, additional 3 zeros to the 8 digits of your binary and acquired 00000010011 which interprets to 19 in https://myeasybookmarks.com/story4293394/bip39-seed-phrase-mnemonics-generator-an-overview