We had a very similar yard at our last house, and had to work quite hard to attract the birds, but once they settled in, they stayed for the three years we lived there, so it was well worth it! Food has been thoroughly covered, so I'll discuss other things that helped us. (I'll come back and post some pictures, which will be small, but you can click on them to get a closer look.)
Make use of the fence.
Our area was also too open, so we put plants and feeders by the fence, as @Aravona has done. You can move your potted shrubs, but more is always better, so I recommend leaving those and adding new ones, especially larger and of the type @Rupert Rankin described, with flowers and twiggy bottoms. Our birds like weigela, if those grow in your area.
Are you allowed to drill holes in the fence? If so, mount brackets and attach flower pots and feeders. If not, there are feeders which can be hung over the top. Rope tied on two fence posts across your corner would provide a nice place to hang lightweight feeders. I know you're under strict rules, though, so if you can't mar the fence at all, just put your feeders as close to it as you can. Birds like to perch on fence posts. If from there, it's only a quick hop to a meal, and a cozy spot, they'll come, and bring their friends!
Provide multiple types of feeders.
Aravona's is an example of a good variety, but there are many more. The swallow-size birds will eat anywhere, but some of the larger birds appreciate wider feeders with bases they can sit on. Flat-tray types are fine too, like your bird table. As you've learned, it's not ideal for suet or wet food, but dishes of seeds on it are fine. We hang suet in cage feeders on hooks or trees. Height's another consideration. Our tallest feeder is over 6 feet, making it easier to spot. Also, some birds are fine in groups, while others prefer to eat alone, so provide some individual feeders too, off by themselves. As for the base, if you can't stick feeders in the dirt like Aravona's, many are available with flat or tripod-type bottoms.
Flowers are very important.
Colors and pollen attract birds, hummingbirds, bees, and butterflies. Also, grubs, worms and other yummy bird-meals live in the soil. Groups of potted flower plants are fine, either on the ground or on benches or other plant holders. Intersperse them among the feeders and shrubs. To mimic a garden, use some pots that are much larger than the flowers, leaving exposed dirt, for rooting around, hiding, eating and dry-bathing. You can put out pots of just dirt, if you don't mind looking at them! The craters in the picture of my annual flower bed are from sparrows rolling around like dogs in the dirt. Unfortunately, every time I try to take a picture of them, they fly off!
Birds love water!
Birdbaths are for drinking, bathing and playing. The type doesn't matter, as long as you have more than one and keep them full and relatively clean. Large plastic saucers, similar to the one on Aravona's feeder, are fine too. Put them all over the yard, on your bird table and on the patio. Some people use upside-down lids from a trash barrel, either aluminum, plastic or rubber.
As you've been told, patience is important, but the right combination of food, feeders, plants and water will make yours the busiest bird-house on the block!