I agree, it's rough to stop. I usually do well at stopping if I feel really full, BUT....if we eat out, ****, I'm paying for this food and I'm gonna eat it! Even after I get full. So when we eat out I do try to get things that would be acceptable as leftovers as well. That really helps.
But the worst part is even if I feel full, sometimes the food just TASTES so darn good....I don't want to stop! Probably because if something tastes that good, that means I'm probably NOT going to get that food again for a very long time. It means it was likely some sort of treat, and I don't want to waste it. Or if it's like cookies in the cupboard, even if I don't feel my stomach is hungry, I still won't be able to stop thinking about those wretched cookies until they're gone. Thus, no cookies kept in the house because I'd like eat a whole package of oreos in one day.
I really want a "normal" relationship with food as well. Have you ever heard of "intuitive eating"? You should read
this post at a blog I've found recently. She's got some good stuff on there. And read the comments because she posts a lot of links on there in response to some of the comments, including my own. I hope it helps!