D.: maybe if one is already slim they can go down a dress size for every 10 pounds, but it's never worked for me either. The last time I lost 10 pounds, I went down a cup size and that's it. Although my pants were a little roomier, I still wore the same size. And although my bra size went down, my shoulders are set as far apart as they've always been. I still wear the same size shirt only the buttons aren't tugging over my breasts anymore. The only time I've ever actually lost inches (not just fat) was when I actually exercised.
I used to have a Cindy Crawford video that I worked out to. When I did that consistently, my body actually changed (the whole thing, not just my "cups"). I didn't diet, I just did about a 40 minute workout daily for about 3 months. I did lose some weight also, but I lost inches in all the right places. If your able, perhaps you could start an exercise regime that targets the areas you want to tone. There are plenty of options other than videos but, I'm not a gym person and can't afford a personal trainer. I bought several different videos that I really didn't care for before I found Cindy. There were 3 different workouts on the tape. Each had exercises for that target specific areas like upper body, core, and lower body. Two of the workouts were 40 minutes and there was also a 20 minute workout. The thing I like about the video workout is that you can do it at your convenience, you don't have to buy anything additionally, you can invite friends (or not), you don't have to dress up, and there's just a one-time fee (the purchase of the video)!
Good luck!