I am a fellow raised bed gardener. I have 4 beds that are 8'x8'. I use the three sisters method in 2 of them. It kept the Indians alive for generations and kept the pilgrims from starving after they learned it as well. In my beds I line the bottom with plain brown dish packing paper and then cover that with a layer of non-colored cardboard. This will help keep the moisture in your garden. I watered it down real good then I added my garden soil on top. It is important to water and semi pack the soil as you fill it as it helps keep the moisture in the soil as well. I also add a tub of earthworms from the bait store to help fertilize and compost the dirt and paper below.
I then measure and mark 2' down the top edge of my boards. I use the marks to make square plots in my beds. In these beds I alternate planting 2 cucumber or squash with 4 corn plants in each 2' square. After my corn is 4" tall I plant 1 pole bean from seed next to each corn plant. The beans will use the corn to climb. The cucumbers or squash are planted at the same time as the beans. They will eventually crawl around the bed and cover the ground helping prevent moisture loss from the sun by keeping the ground shaded. The corn is a heavy nitrogen feeder and the beans help a lot because they are nitrogen producers.
So all in all I am able to get a total of 24 corn plants 24 bean plants and 16 squash/cucumber/pumpkin in a 8'x8' square. Looks like a jungle as it grows tall but I have been doing this for years with no issues. If you are an OCD gardener and must have perfect rows this is not the method for you but again if it was good enough for the Indians it is plenty good for me.
Sorry if tldr I tend to get long winded at times. I'll post a link to the three sisters method to give you a better idea on how it is set up. LINK
she recommends 10'x10' beds but mine do just fine at 8' square. All that said if your garden is only getting 6 hours of sun a day then I think that is the major culprit. Minimum 8 hours for nearly all fruits or veggies. Good luck turning it around.