I was also having some problems with my one handed backhand returns. At that time my role on our team was to play the forehand side during doubles. So I was wanting to strengthen it on that side. My local pro started me out slowly and what he wanted me to do was to let the ball come into my body more than try to hit the ball so far out in front. That took a little getting used to. I had to keep my arm and wrist bend firm and let my should point the way. When I think about hitting my backhand I think of two shots: One that is angular (or circular) for power groundies and linear for when I get shots into the body and sometimes for going down the line. The return of serve for me is a linear shot. What I also do now is to pivot a little on the back foot which allows me to go crosscourt or down the line. Let your shoulder determine the direction of the return.
By the letting the ball come into the body more, you give yourself more time which is exactly what one needs in that situation. Don't forget to have a short backswing too.