Thank you all for the encouragement on sticking with the plan to knit "too small". As you can see, I've managed to resist the urge to rip so far, but it's been an uphill battle. I think I'm reaching the point of no return, though--the stage at which I've knitted enough of a project that denial kicks in and nothing can get me to rip back--so I may be out of the woods for the time being. I'm starting to look forward to seeing how this fits.
Several of you made really interesting comments (and due to Blogger's refusal to release your email addresses, I couldn't respond). MJ's explanation of how she decides on measurements to use when she designs for herself was especially illuminating. If you haven't read it, check the comments to the last post. I design some of my own stuff, but my approach is decidedly less sophisticated. I usually "design" by holding the flat pieces of knitting up to my body as I go and decreasing or increasing according to how it looks. This works even less well that one would expect. Her method would probably result in garments that actually fit.
I was also struck by Tracy's comment that she always picks the size that comes closest to her actual measurements without going over. (Sort of a "The Price is Right" approach.) I have to admit, I read this three times to be sure I was understanding what she was saying. I usually start by finding the size that is closest to my actual measurements without going under. But considering the stretchy nature of knitted fabric, her method really does make much more sense, unless you want a drapey, oversized sweater.
And I have to acknowledge all of those who commented that they seem to be bigger than they think they are! Truly, I can relate. But since that issue only seems to affect my, um, lower body, it doesn't come into play in my knitting, because I have a strict rule about never knitting any garment intended for wear below the waist--ever since that unfortunate bikini incident when I was a teenager.
Oh, and as for the yarn, it's Jaeger Roma. It's not a yarn I would normally choose, because it's mostly viscose with a bit of nylon and angora, but I got it on sale for $1.99 for a 137 yard ball (www.smileysyarns). It retails for $10.95 a ball, so I couldn't resist trying it. To my surprise, it's a really nice yarn. It has a rounded construction and is smooth and soft. It is also very stretchy--almost elastic. The ball band recommends a gauge of 22 stitches to four inches with a size 6, but if you are going to buy some, you should definitely disregard this. I did multiple swatches, and anything smaller than 19 stitches to 4 inches makes for a somewhat stiff fabric. I'm working it at 18 stitches and 28 rows to four inches, and I love the results. I washed my swatches and there was no change in gauge. If you're counting, this means you can knit a women's size medium sweater from this stuff for about $20!