Diane,
I've handquilted for years and my stitches are not quite as "large" or "long" on the back of a quilt as on the front. Practice, patience, and consistency of stitch (more important that size) will win the day for you. Most quilters feel like trying to back a trailer when they first begin handquilting, it's awkward at first! More quilters use a frame or hoop than those who do not, but beautiful work is accomplished either way, so keep at it and soon you will have the rhythm and stitch you seek.
Jan in VA