Portion Control.

I've found using smaller plates really control my portion size at meal time. Although i do cook to portion, mentally seeing my plate to the brim, despite it being a smaller plater...psychologically helps me into think i'm full and/or i've had enough for the meal.

Another thing that helps is water, drink a full 10oz cup during my meal certainly quinches my thirst and aids in keeping my appetite in check. Something i tend to go by is keep 1/3 for air, 1/3 for food and 1/3 for water...puts things into perspective during my meal.

This all goes in hand with making sure you have a balanced meal to begin, both high in fiber and protein

Try to have a variety of things with each meal or snack. So if it's a high calorie food like almonds or peanuts, I limit myself to the portion I can 'afford' per my food diary and then fill in the hungry space in my stomach with other stuff. Fruit and nuts is a pretty common snack or light meal for me. But I can eat a lot of peanuts (and I'll regret it later both for the stomachache and the calorie hit), so I have to be careful. I try to do that at all my meals. And I make sure to savor every bite of my portion of my most loved foods. If it would help, just remind yourself you don't have to eat ALL the food RIGHT NOW, there will be more later.

I feel you there. I struggled for years with my habits of overeating, almost as if it were due to scarcity (which it was not). I'll share with you what works for me and maybe it will work for you:

1) Writing down everything I eat immediately after or right before I eat it. Example, if someone brings donuts to the office and I break and eat one, I write down that I ate 300 calories. Adding another 300 right after that puts me at almost half my calorie allowance for the day, and just seeing it on paper (well, on FitnessPal), really helps prevent me from reaching for a second (...or a third).

2) If you are eating a dangerous food (one that's hard to stop eating), take an appropriate portion, and eat it in a different room. If you find yourself standing in the kitchen eating fistfuls of cereal until half the box is gone, then next time you have that craving, measure out one serving, put it in a bowl, put the box back in the cupboard and carry your bowl to a different room to sit down and eat it. When it's gone, it's gone!

3) After eating a normal serving, wait twenty minutes. You'd be surprised to find that you no longer crave more of it, or you will find that you actually are not hungry.

Hope those tips help!

Is weighing and recording your food not helping?

Playing off of what IronSmasher said, I only really started to understand portion control after using MFP for a few months to track food. I now have an idea just by eye of what constitutes a serving. I can have more if I want but I can't pretend like I don't know what I'm doing. After enough time measuring cups and ounces and tablespoons, you can start to just understand.

Perhaps low calorie veg and salad could help, stuff you can go fairly nuts on.
A low cal soup starter.

You're also going to have to try and figure out if you're actually hungry or not. It doesn't seem to be a case of you losing track of portion control, or not being aware of how much you're eating.

It could possibly be that you're not eating enough and that you've miscalculated how much you should be eating, or you're under counting your calories.
It could be that you're trying to use eating foods as a way to avoid dealing with feelings or issues causing you stress and upset.