I am pretty much self-taught too, but when I get to the end I run a basting stitch across the bottom, then release it from my leader. I pin it down, then do the stitching a little less than 1/4" in from the edge then go back and do the last row of quilting.
I use Red Snappers to secure my quilts to the leaders and this is the only way I could figure out to do it since the bottom of the quilt is always secured into the Red Snappers.