I would disassemble the jacket and trace them on to paper to make the pattern. Make sure there is plenty of paper around the drawn pattern to allow the re-drafting. If there are panels that are cut up or damaged, simply lay them flat and glue a layer of some stiff fabric over it to give the integrity required.
Then using another jacket than fits you, lay the pattern pieces over your fitting jacket and extrapolate the changes by drawing around the pattern those areas that need correction. Most jacket etc, have common pieces, front left, front right, yoke, sleeves etc.
Note: be wary of the right and wrong sides, and leave sufficient seam allowance around the actual part size.
I have done this once, on a simpler garment and it worked well.
Tony