I took the index of your words, transformed the amount to binary, included three zeros, calculated the sha256 digest, took the first part of the hexadecimal to convert it to binary, additional a few zeros into the eight digits with the binary and obtained 00000010011 which interprets to 19 in https://throbsocial.com/story20740966/getting-my-bip39-words-to-numbers-to-work