I have been knitting since my grandmother taught me how when I was a teenager. I have made many sweaters, hats, and other garments. Because I am a very small person, I have had to adjust the proportions of nearly everything I have made, including many of my hats. The math is easy (see my bio description in “About Me”), but it has been hard to judge how much of an adjustment to make — as many others have noted, you can knit all the gauge swatches you want and hang weight from them to simulate the pull of the full garment, but so often you have to ravel out most of all of what you have knit and to start again. My advice to all: don’t be afraid to junk all that work and ravel out. You will be happier in the long run because once you get the garment to fit right you will be more comfortable wearing it and you won’t have a lemon sitting in a drawer.
NOTE: The photographs I include do not always show the garments in the way they look on a person. In the case of the sweaters, this is due to the hangers — the actual garments do not pucker or droop at the bottom!