I think your springs are sagged. Shocks aren't really going to affect the ride height especially when stationary. the springs hold the vehicle at a certain height. The bags will air up and help with that but when the air is out of them, the springs will dictate the height. Maybe they are sagged from overloading but I have to admit, that condition is pretty rare. Springs are a lifetime part and never need to be serviced. Have any rust issues? Perches rusted?
Remedy, get a new set of OEM springs and throw them in. Cheap and easy to do.