When you are making a sweatshirt jacket, plan to try it on before finishing.  After you have covered the pieces and "quilted" to your satisfaction, trim the pieces and baste them together with the seam allowance you plan to use.  Try on the jacket to see where you might need to make further adjustments.  For example, you might want to indent the waist a bit at the side seams, make the sleeves shorter, tighten or loosen the neckline, shorten the jacket, or even add a simple collar.