and check your seam allowances and accurate measurement after each two pieces are sewed together The probem may be at the beginning and nt the end of piecing a bock. Each section should be measured for accuracy and correct at that point.

If all your blocks are the same size then it doesn't matter if it is a scant 1/4". I see a lot of quilters try for the scant 1/4" and usually only some of the blocks end up with the same size seams as the next one. Whatever size between 1/8" and 1/4" that you can consistently sew then that's the size you want. I found the PERFECT scant 1/4" foot for my machine and it's worth it's weight in gold. Took me years to find the perfect one.