Diets and Women's Sizes

I'm on a diet. It's been mildly successful so far. I've lost 2 .75 inches around my waist in a few weeks. I consider this a major step forward. It's a damn good thing I actually like salads.

I've been trying to figure out my end goal (size 12) and what I need to lose to get there. The problem is there are quite a few different measurement charts to go by. The US Standard size chart, which the clothing manufacturers in the United States aren't required to use, for some reason, states thus:

Size 10 (might be cool to be this tiny again): bust - 32.5, waist - 25, hips - 34.5

Size 12 (ultimate goal): bust - 34, waist - 26.5, hips - 36

Size 14 (goal for vacation at the end of July): bust - 36, waist - 28, hips - 38

Apparently, this sizing standard is falling into disuse by everyone because of its age, vanity sizing (yes, I believe it exists) and designers whims.

By contrast, the majority of catalog sales measure sizes thusly:

Size 10 : bust - 37, waist - 28, hips - 38.5
Size 12 : bust - 38.5, waist - 29.5, hips - 40

Size 14 : bust - 40, waist - 31, hips - 41.5

I would love to make it to the US Standards idea of size 12. I'd feel so skinny it's not even funny. However, just to get to their size 14 waist, I'd still have 15.5 inches to go in three months. I think the catalog one is a little more doable. It makes me wonder, though, I'm already wearing size 18. It doesn't take dropping almost 16 inches to lose two sizes, does it?

Oh, did I mention I keep putting off the exercise portion... *stupid stupid*