Eden, I have the same issue. Clothes are getting bigger while the sizes get smaller. A few years ago I weighed less and wore a petite 4. Now i wear a 2 or 0 (which is ridiculous). I am a 52 year old woman who does not and will not shop in the kid's dept. In fact, i was at a vintage store last fall and saw a really cute dress in a junior size 3. It looked like something I had in the sixties. I couldn't get it over my hips. The only 2 stores I can walk into and buy off the rack are Ann Taylor and the Loft. I order almost all of my clothes from J Crew or Banana Republic on line. Banana Republic did just open a petites store in a mall not too far from me. I thought I had died and gone to heaven when I could walk into a store and buy a t shirt. Yes, I am short and I weigh what I should for someone five one. But I am a woman with curves and a couple of jingly parts that remain despite the exercise.
There was just an article about this in the Boston Globe. It is a real phenomenon that clothing manufacturers are doing to the public because people don't want to admit they are getting bigger. I confirmed it when I went to Europe last year. I tried on a skirt to buy that said it was the equivalent of an American size 4. It was way too tight, so I bought the next size up, equivalent to a 6. That's my "real" size!