You certainly sound like you have the symptoms of sugar addiction — but you may also have hypoglycaemia. It appears that you may have a hypersensitive reaction to sugar — you crave sugar and get agitated when your sugar levels are dropping.
If you are hypoglycaemic, it is best to take sugar out of your diet. Hypoglycaemia occurs when the insulin increases to match your sugar intake — thus the higher your sugar intake, the more likely you will experience a 'crash' as the insulin increases in its attempt to transport all the sugar to your organs— You have indicated that you are eating smaller portions and exercising. These may be useful manoeuvres, but you would do better to cut out the sugar completely and decrease your carb content in general. Stick with green and brown vegetables for your carbs. Eating a diet higher in protein and fat may help to counteract some of your symptoms.
There is evidence now suggesting that people who have a family history of addiction may also be addicted to sugar. It is not uncommon for alcoholics who stop drinking to turn to sugar instead. We have found that there are genetic abnormalities (D2 receptors) that are in common with addiction and obesity. If you are genetically predisposed to 'liking' sugar more than another person, you may well be fighting a harder battle. But it is not impossible. People who realize that they are addicted or 'hypersensitive' to sugar (that is crave it obsessively, see my posts below) find that they do much better when they stop eating sugar. The cravings go away, and stay away... unless you take another sliver of a cake!
Hey, Bonnibell --
Alcohol is sugar-based and is therefore very similar to the way sugar acts in our systems. There's a reason that the Big Book of Alcoholics Anonymous recommends the recovering alcoholic carry candies in his/her pocket -- sugar mitigates alcoholic cravings.
There are no ifs ands or buts on the subject of food addiction: it is as real as cocaine or alcohol addiction and, in fact, affects exactly the same pleasure/impulse control centers of the brain as recognized drugs. This is especially true of what David Kessler calls hyperpalatable foods -- foods dense in calories from sugar/fat/salt. Oxford University Press has just published the medical textbook on the subject: Food and Addiction: A Comprehensive Handbook, edited by Kelly D. Brownwell & Mark S. Gold. And I've just published the first holistic approach to food addiction, The Hunger Fix, which is based on that cutting edge science.
These addictions actually destroy the dopamine trasmitters, which sharply reduces the individual's cognition, motivation, punishment, reward, sleep, mood, attention, learning, memory and sexual gratification, undermining the very impulse control needed to resist the addictive substance.
The bad news on food addiction is very bad indeed, but the good news is that, with daily maintenance of the right food plan and plan of action, it is an addiction that can be lived with in a certain amount of peace.