Leave the ice out of the smoothie as frozen fruit covers both ingredients, but doesn't water down your drink.
1/3 C frozen blueberries
4 - 6 large frozen strawberries
1 whole peeled banana
1/2 C skim milk + 1 tsp vanilla flavoring, (vanilla soy milk is a tastey substitute)
1/4 C whole milk plain yogurt
2 Tsp local honey (local product supposedly is helpful to boost your defense against local allergens)
Pulse in the blender until smooth. Yields about a 10 -12 oz. drink.
I don't see a smoothie as a low cal thing, but more as a meal substitute. Enjoy.