Don't feel bad - I have made tons of quilts and finally on the last one I did I feel happy with my binding (I do hand sew to the back - just wait for days my hands will cooperate!). I followed Sharon's method religiously and it worked!
I echo everyone else - give yourself more fabric - either sew a 1/4" seam or cut bindings wider. I still have a project that I cannot turn the bindings on - one day will take it out and do it right.