I use a 14" hoop, bigger and it falls off your lap. And the quilt sandwich is taut.
And what makes the difference is the way I quilt. I do a punch and poke stitch, similar to what should be done for needlepoint:
the needle goes straight down into the fabric
The hand underneath pulls the needle through, but only enough to turn the needle and poke it back up
The upper hand takes the needle pulls it up to the surface and pulls the thread taut.
The hand underneath, stays underneath.
After practicing this for about three days, your stitches and spaces should be close to the same size on both the front and back.
It also takes practice to do the running stitch, which I can't do.