I know (of all people) that weight just doesn't want to come off sometimes.
If you have the money and the time, I encourage going to the weight watchers meetings. You may be eating all right and exercising, but you have to learn how to do it the right way. It's going to sound insane, but you actually eat a lot when on the plan, and it just comes off (even wo exercise!) you can expect to lose 5-7 lbs the first week, and maybe 1.5 - 2 every week after that. It's a slow process, but it works.
Be sure you're getting enough fiber. Cheerios, dried apricot and skim milk is a favourite breakfast of mine that is more than satisfying and it gives me tons of nutrients. Be careful on whatever diet you're on...You may not be getting the right amounts of nutrients you need to make your body work the correct way.
We are a complicated system....So we have to take complicated measures!