What omen80 said. Anything that is labeled "fat free" is usually a chemical sh*tstorm loaded with sugar.
Go for the natural full fat yoghurt, or greek yoghurt. They both have their own probiotics if that's what you're into, and add your own fruit for flavour (don't get flavoured stuff), it'll taste nicer and be healthier too. Stick with berries, etc. for their low sugar content
A favourite of mine is greek yoghurt with chopped banana, with half a teaspoon of coffee mixed into it. Be careful about calorie count though, since fat is so caloric dense. It's satiating though