I have often been asked how large my quilted jacket patterns are sized, and often even the largest size is too small.  A possible solution is to buy a sweatshirt large enough to be generously sized on you, then take it apart and use it as a base to create your jacket.  Quilt the patchwork to the wrong side of the sweatshirt, then reassemble the sweatshirt.  There are many patterns available to guide you on creating jackets from sweatshirts.