Maybe talk to a dietician. Sugar is itself addictive. Some studies evidenced that it's more addictive than cocaine and lights up the same parts of the brain.
I personally eat a near-zero sugar diet to protect my teeth and for other reasons, but when I was a kid/teen I ate sugar all the time.
Off the top of my head:
-Do you eat enough fat? This was a big problem for a lot of supposedly diet/health foods- they cut the fat as much as possible, but replaced it all with sugar. So like, lowfat yogurt = high sugar yogurt, as an example. To eat low sugar, you still need enough calories and satiety- so you need adequate protein and fat. Many types of fat are healthy- generally the least processed kind, and kinds that were prepared in ancient times and without much heat.
-Are you eating a lot of high glycemic load foods? Sugar itself is incredibly high glycemic, but so are most grains, potatoes, and other starchy foods. You can find lists of high glycemic load foods online for reference (like
here), but it's generally related to how much carbs something has compared to how little fiber. When a person eats a lot of high glycemic load foods, they get big blood sugar spikes that result in a crash a couple hours later, resulting in cravings for more carbs/sugar. On the other hand, a low glycemic load diet keeps the blood sugar at a more steady rate through the day without the crashes and cravings. You can buy simple blood sugar test kits online, or you can just make sure to focus on a low glycemic set of foods. If your meals don't keep you feeling satisfied for 5+ hours without needing to snack, there's a good chance that your meals are causing blood sugar spikes/crashes.
-Some fruit has lower sugar than other types. So if you want to eliminate your sugar addiction, consider less sugary fruits like berries as your treat, especially blackberries and wild blueberries, which have fairly low sugar and high fiber so it absorbs more slowly. Some fruits like mangos are really high in sugar.
-As a vegan, you might want to check for nutrtitional deficiencies or consider additional supplementation. There's a high probability that at least some of these nutrients and others are low in your diet unless you are really vigilant to get them: B-vitamins, fat soluble vitamins (retinol, Vitamin D unless you get a lot of sun, Vitamin K2), calcium, zinc, magnesium, iron, and long-chain omega 3 fatty acids. A simple way to balance a vegan diet without artificial supplements is to eat a couple servings of mussels, oysters, and clams per week. They're not vegan, but they don't have centralized nervous systems, and they are high in most of the nutrients that tend to be harder to get on a vegan diet.