Not to worry. Weight gain gives a man the impression of a smaller penis. As fat accumulates on the lower abdomen, the apparent size of the penis changes. "a large prepubic fat pad makes the penile shaft look shorter, " as we age the penis tends to undergo an actual (& irreversible) reduction in size (in both length & thickness). A hernia that is large can push on the prepubic fat pad and make penis look smaller.
Abdominal wall. Most likely your lower abdominal wall contour/shape has been distorted by the hernia. A large hernia can impact this contour, as can excess fatty tissue. There is no direct relationship between hernia and other body part sizes. You should go in and see your doc, a referral for surgery consult/hernia repair is in your future.