First, I didn't notice any missing points in your block either! I think it's very well done.
That said, I also agree with platyhiker's pinning suggestion (except I do the alignment pin in reverse - start with top piece then do the bottom piece). I do not mark the 1/4" seam line but do put stabilizing pins about 1/4" on both sides of the stabilizing pin. Another trick you might try is if your 1/4" seam is great and consistent on any given unit in the block, when getting to the 'point' of said unit, stitch 1-2 thread widths into your seam allowance over that specific intersection. Your point should show up and no one will ever notice that you seam 'wiggled' a thread or 2 in any given spot.