Ange, sorry to hear you're having a rough time with this unit.
Try reducing load size by about 50% and then slowly working up to whatever size load it will handle in a satisfactory manner. Also mix the sizes in each load, i.e. some large items, some medium-sized, some small. And try the various tricks posted above for getting more water into the cycles.
It's possible you got a bad one, which can happen with anything, even Mercedes automobiles. Ask your appliance dealer to set one up at their shop so you can observe the cycle, and see if it's the same as yours: water level, speed of agitation, etc. etc. Better yet ask if you can bring in a batch of laundry and have them observe what you're doing to see if there are any mistakes you're not aware of. Then you can observe the machine at the appliance shop operating under controlled conditions, and see if it behaves in a similar manner to yours.
Or ask the repair tech to observe a complete cycle, starting with watching what you're putting into the load. This may require getting the tech's supervisor to approve, but it could solve some issues right away by pointing to a diagnosis.
Machines with impellers of this type are the majority in most parts of Asia, including Japan where people are used to good technology and have little tolerance for bad. They are also fairly common in Europe and the UK. Impeller machines are new in the USA, and I would guess take a bit of a learning curve to get used to, in terms of things like load size and load composition and so on. General Electric is too large a company to introduce something that's not been tested thoroughly. While they may not be up there with some of the European units in terms of refinements, they are certainly competent at building appliances that perform according to specifications and are reasonably durable.
Or if, after all that, you still aren't satisfied with that unit, see about exchanging it for something else, or at last resort, sell it on Ebay or some local classifieds site, and get something else. Even if you lose a couple hundred in the tradeoff, it's better to have a machine that works for you, because you're going to be using it for years.