re: Help ID'ing my grass

That top close up photo is not St Augustine - as the leaves are not opposite but rather alternate in orientation, so centipede. Can’t tell anything from the bottom closeup. But your original top 2 photos sure look like St Augustine, though that bottom photo from original post does not. Sure you don’t have a mixture of two grasses?

Here’s a photo of centipede on top (leaves alternate, and tip of leaf blades pointed) and St Augustine on bottom (leaves opposite, blade tips rounded).