Bottle feeding question

They say to make sure that the baby does not get any air in the bottle b/c that can cause gas..people say to make sure the nipple is full but what happens if you put 3 ounces in the bottle and she drinks all 3 ounces, should I always put in extra formula to make sure there is always formula in the nipple? or is it ok for her to drink it all ? thanks.

Re: Bottle feeding question

I always take the bottle away when the nipple is a little more than half-full.