is the problem while quilting? do you pin every 4" in a grid? then quilt it- to the extent determined by the batting? (some batts say you have to quilt every 2"-4" some allow up to 10" between quilting lines)
then when the quilting is finished do you square it up? then add the binding? it is normal for (some) distortion after quilting- it is like doing embroidery or applique- as it is quilted the fabrics are drawn up to some extent- so a little bit is normal- that's why the quilt needs to be squared up after quilting/ before the binding.