A couple of suggestions for those pesky points.
Check the 1/4 inch seam to make sure it is accurate.
Sew with a thin piecing thread. It doesn't take up as much space in the seam allowance.
Draw the 1/4 inch seam line if needed.
Check the block after pressing and be sure there are no folds in the seam allowance.
Make sure you are cutting correctly. Try the cutting mark lined up over the edge instead of right on the edge. That line counts and will add up if you start with a piece that is cut short.