How to Pull Up, Plump Out, or Fill in "Sunken-in" Corners of Mouth.

I've had 2 people put filler in my naturally VERY thin lips and i got the same result from both of them - The corners and sides of my mouth remain sunken in. They can plump the centers okay, but the outer half-inch of the lips remain very thin and the corners so sunken in the my lipstick bleeds out the corners constantly. I have to keep wiping away the lipstick that collects there, and i don't like the "Betty-Boop" look of pouty in the center only, skinny on the sides. What is going wrong here?