I took the index from the words, transformed the range to binary, added a few zeros, calculated the sha256 digest, took the very first Component of the hexadecimal to convert it to binary, added three zeros to your 8 digits from the binary and obtained 00000010011 which interprets to 19 https://pageoftoday.com/story4209500/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase