i found the easiest way to regulate my stitches was to regulate the speed of my sewing machine.
since my sewing machine doesn't have any other way to regulate speed aside from the pedal, i had DH build me a brace that i insert my pedal into when i want to free motion quilt.
the brace keeps the speed of the needle constant that way the only thing i need to concern myself with is moving the fabric at a constant pace.
it works like a charm since no matter how hard i press down on the pedal the brace prevents it from speeding up the needle.