DH made me an portable extension for the left side of my sewing area, and that helps take care of the weight, so I'm not always tugging at the quilt when sewing the binding on my king and queen quilts.
I always make my binding - once I have completed the top of each quilt, wrap it onto a empty circular tube (wax paper tube, etc) and label it so when I get the quilt sandwiched and quilted, I go into my binding drawer and there it is all ready to be sewn on. (I usually have about 10 or so bindings completed and just waiting to get back my sandwiched and quilted quilts - that's why they need labels).
Mitered corners I have finally mastered - a friend told me before I get to the corner to be mitered - stop 1/4" from the edge and TAKE IT OUT OF THE SEWING MACHINE.
Fold the binding up even with the sewn down binding (which you just stitched down, (SHOULD BE ON YOUR LEFT SIDE), fold over the piece to be next sewn down ON YOUR RIGHT SIDE - make sure it is even with that (YOUR LEFT) edge and then put your needle in the next (YOUR RIGHT) side starting off the edge of that binding, stitch down the next (YOUR RIGHT) side of your binding. It really works well for me. I'm not really great at putting down in words how to do something....but I hope you can figure out this procedure.
I love to hand sew the binding onto the finished quilt, I find it relaxing.
Your quilt is beautiful, love the colors you used.