I took the index of your words, transformed the amount to binary, extra three zeros, calculated the sha256 digest, took the primary Portion of the hexadecimal to transform it to binary, included 3 zeros on the 8 digits in the binary and got 00000010011 which translates to 19 in decimal. https://wearethelist.com/story20742335/the-definitive-guide-to-bip39-seed-phrase