I agree with Nevaeh that pictures are very important. You see yourself in the mirror every day, so of course you don't notice the changes as much as someone who, say, only sees you a few times a year. Before pictures are sometimes difficult to take at the time, but for this exact reason, they can be insanely helpful.
I lost almost 50 pounds once and still didn't change sizes. I just went from wearing a tight 22 to a comfortable 22. I got so frustrated that I gave up, and now here I am, another 20 pounds heavier than when I started that time. I just have to keep telling myself it will happen eventually! And when it does start happening, the next size typically takes fewer pounds to reach than the first size change took, if that makes sense.
Highest known weight: 324
Weight on morning of DS surgery: 308.5
Got down to about 185 before pregnancy;
Benjamin David born March 24, 2012, 7 pounds 11 ounces