My intuition fails me

As a long time student (many workshops and books read) of Intuitive Eating and Mindful Eating, I should long ago have reaped the benefits of those styles of living resulting in permanent weight loss and eternal happiness. Why has even weight maintenance eluded me in the face of all this knowledge. Because I'm still not sure when I've had enough.
As part of an exercise in one of the workshops I took, we all went out to lunch together to Pei Wei's. Everyone--except for me--ordered a "healthy" lunch. I wanted to be "honest", so I ordered honey shrimp over white rice. We were instructed to eat until we had "enough". I ate about three bites and felt that I had eaten enough. The rest of the group ate most of their meal. About two hours later, I was hungry while the others were not. The instructor said that we should not feel hunger for about three hours. If we did, then we had not eaten "enough". So what is enough???? I felt that if I had eaten past the point at which I stopped that I would have been eating past "enough". I wanted to eat more. My brain and my mouth wanted more but I knew that my stomach didn't need it yet. But the amount I ate did not keep me satisfied for three hours.
And this is a problem for me. Is it that I don't recognize "enough"? Do I stop too soon? Is my body different so that I need calories in two hours instead of three even if I've stopped at the "right" time?
Here's the thing: One sip of a drink satisfies my thirst. One bite of food satisfies my hunger. Obviously that's not good enough. How to eat until "enough"? I don't know. Is my intuitition off?