My jacket is like that too.
I bought it a little big to make sure the arms would still be long enough while riding and a little bigger around so I could wear something underneath if needed, like a sweatshirt or something.
My jacket is about 11 years old now and hasn't shrunk as time has gone by, I haven't either.
I know this is vain but I fold the bottom of the front up and behind so the "front bunch" doesn't happen.
I do get some WTF are you doing looks when I do this but, whattya gonna do?
So, if you can't return your jacket, or sell it to someone for what you paid, this may be an option.

Dan