Don't try to collect all fabric in your left hand, instead put your left middle finger behind the stitch, and collect just one fold of quilt fabric with your thumb. Let the rest of the quilt drape over your left arm. This is how I hoopless quilt big or small stitch. Give it a try.
If you can't get comfortable with that, I recommend you QAYG keeping rows of quilting sandwich a maximum of about 18", then when you attach the 18" quilted strip to the remaining quilt, the maximum you will pinch is 18" to reach the attachment seam that now needs to be quilted.
Good Luck!