If you rotary cut your pieces correctly. Stitch a consistant 1/4 seam. That leaves the pressing.
Are you ironing or pressing? Sounds to me you are 'ironing'
your quilt pieces, thus getting them all out of shape. You are overdoing it. Press your sections as you piece them. Square each section as you go. Use a dry iron and no ironing stuff.
Your points will line up and your blocks will be square.