Sugar can bother people in different ways, so that may be a thing for you. I don't necessarily feel full if I eat sugar, but more than a little leaves me feeling slightly light headed and nauseous. Which may be pre dumping syndrome kicking in, idk?
Also, pro-tip if you like blueberry flavored yogurt. Freeze your blueberries and add them to vanilla flavored yogurt. The blueberries are so good frozen and they start to thicken/ freeze the yogurt so it feels like a treat, instead of just yogurt. That's my daily snack.