Sounds crazy I know, but thru much trial and error and trouble shooting with experts . . .turned out, my issue was thread. I now use only Aurifil thread as its approx the same size as the threads woven in my quilting cottons. Additionally, needles make holes each time they enter the fabric. The hole displaces threads, so take up room. Now, I use only Schmetz microtex 70. My quarter inch seams are now perfect.