Let it Flow
Until you're comfortable enough to sell tickets to the gun show, cover up your arm sag with a drapey top, a shawl, or some other non-form-fitting sleeve. It might not be a solution, but it'll definitely hold you over until you're satisfied with the results.
Strike a Pose
It's a trick every model and society girl knows: Place your hand on your hip to shave inches off your arm flab. To do: Bend the arm roughly 45-degrees with your hand on or slightly above your pelvis. Say cheese, and smile pretty.