I have been quilting for almost 30 years now and I STILL have problems with doing the miter to connect the ends so don't feel bad!! I saw instructions somewhere that you overlap your binding edges, then make a small snip on the cut edge making sure you have over 3" on each end of the binding. Then open the binding using the cut snips to guide you to line it up correctly but I forgot what goes where but eventually I am able to get it lined up properly.
I recently saw Patrick Lose, the original designer of Moda Marbles (my fabric tonal fabric) on F&P. He showed a slightly different variation on sewing binding in a corner. He stops sewing just at the 1/4" end then pivots the quilt and sews off to the corner of the quilt. This give you your perfect miter. He cuts the thread, and then fold the binding as you would normally and continues to sew to the next corner. There is more to this but you really have to watch him doing to understand the concept. I was skeptical at first but it works and I now I do it his way. I think it was the 2300 series but not sure when or if F&P will let you watch the series online.