I took the index on the words, transformed the amount to binary, included three zeros, calculated the sha256 digest, took the very first part of the hexadecimal to convert it to binary, added 3 zeros to the 8 digits of your binary and received 00000010011 which translates to 19 in https://7bookmarks.com/story18727145/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting