hmmm I think I would have ( I know , kinda late now -- maybe u could add it and still do it this way??) made the edges just a bit longer, folded then toward the inside of each cup, then hot glue the " underwire areas" together, thus catching the " binding" in the glu area. Turn the wrong side out and trim any extra quilted fabric to the edge.
or
glue underwire areas together, then glue or hand stitch some sore of large trim ( pearls, rick rack gimp, etc) to hide the glued areas
after going back I see u covered the side straps too.. most of the ones I've seen were made into purses and the side straps were cut off...leaving just the shoulder straps for purse handles..
ignore me if u making a truely quilted bra.... smile