Need help with Biscuit recipe

I may be able to make whole wheat bread, but I have problems with biscuits. I've made this recipe about 4 times and while they are okay, they could be better. I've tried white flour and whole wheat, regular milk and soymilk. They never really rise or get fluffy at all.

Here's the recipe I'm using:

2 cups all-purpose flour
4 teaspoons baking powder
2 tablespoons granulated sugar
1 teaspoon salt
1/3 cup butter or margarine, cold
3/4 cup milk, cold

1. Preheat oven to 425 F Mix first 4 ingredients together in a bowl.
2. Cut in butter with a pastry blender or a fork, or two knives, until crumbly.
3. Add milk.
4. Stir until it forms a ball.
5. Add a bit more milk if necessary to make a soft dough.
6. Roll or pat to 1 inch thick.
7. Cut into circles with a biscuit cutter or a floured glass.
8. Arrange on a greased baking sheet.
9. Bake in 425 F for about 10- 12 minutes or until risen and nicely browned. (in my oven it usually takes 15 minutes).

Any suggestions?

Barbara