> 2 cups of flour works regardless of the size of your cup

This couldn't be more wrong and no serious baking is done by volume for dry ingredients (flour, yeast, sugar, salt preferments, other additives).

EDIT: It is clear from your other comments you almost certainly know what you are doing, but this particular part is very wrong. You can't measure powders reliably by volume, regardless of sifting, tapping, or tamping.