I took the index in the words, converted the selection to binary, included three zeros, calculated the sha256 digest, took the initial A part of the hexadecimal to transform it to binary, added 3 zeros towards the 8 digits of your binary and received 00000010011 which translates to 19 in https://bookmarkbirth.com/story18930184/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting