If woolen clothes shrunk in the wash, you can try to reduce the damage by ironing the wool. This is done with a steam iron. Take a wet towel and place it on the jersey. Set the iron to steam. And then ironing and gently stretching. Make sure the towel stays wet. Do you have ironed the whole sweater, put it after lying out to dry so that the form can get. This is not a 100% guarantee of success. If the two sizes become smaller, it is probably too late.