You build on being light and right instead of loud and wrong. Realize that the edges of the cords are connecting and begin to strengthen the muscles involved in the coordination to make the tone louder.

What are those muscles? Primarily the lateral cricoarytenoids, which function it is to adduct the vocal cords and close the rima glottisdis, protecting the airway. Strengthen those muscles, and the added volume produced by a combination of increased air flow and increased vocal cord surface area contact via the activation of the CA muscles, and you will build to a consistent and voluminous tone.

To be sure, there are several other muscles involved, working together to maintain cord closure and lengthening respective to the tone produced. However the lateral CA muscles directly affects the amount of compression applied to the vocal cord, resulting in increased surface area contact and a perceived louder sound.

Continue on and focus on the exercises designed to maintain cord closure while strengthening cord compression.