When I am making formula for the baby I generally put in water up to the 6 ounce line. Then I add three scoops of formula. But then I have noticed that instead of it being 6 ounces, (because of displacement) there is really a little more than 7 ounces. Am I doing that wrong? Do you put the formula in the bottle first? And then fill it up to 6 ounces? Or would you fill it to less than 6 ounces to account for the formula taking up space too?