I took the index of your words, transformed the amount to binary, included three zeros, calculated the sha256 digest, took the 1st Section of the hexadecimal to convert it to binary, included three zeros towards the 8 digits of your binary and obtained 00000010011 which translates to 19 in decimal. https://pageoftoday.com/story4576767/an-unbiased-view-of-bip39-seed-phrase-github