Thin Centipede Lawn

I'm really struggling with my centipede lawn in various areas. I bought a new construction home a few years ago and it was sodded with centipede. I have followed many of the guides found online about centipede care but it really never fills in and gets thick. This year I took the leap and got a soil test done which showed I had some pretty bad soil but the p.H was at least in the range for centipede. It appears in the areas that are struggling, the grass never really roots and stays on top of the soil and dies. Anyone care to take a look at the pictures and give me any advice?