Yep, that fixed it. Even though the UI was saying that I was on Point (even when manually selecting the file and regardless of override) I think it was forcing Bilinear.
And to get it pixel perfect I just need to multiple the pixel size by the quad size, so 1.125 to go from 16-18.
Edit: Just to add, not sure how this happened since it was working previously with the same texture. Just somehow the quad file got broken without being touched.