I took the index of your words, converted the range to binary, added a few zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to convert it to binary, extra 3 zeros to your 8 digits with the binary and got 00000010011 which translates to 19 https://bookmarkforce.com/story18904945/getting-my-bip39-words-to-numbers-to-work