Garden companion planting plans

Would love feedback on my plans for a garden with emphasis on companion planting and diversity. Total plot is 25x12, each smaller plot is 4x5, the three circles marked with C are buried green cone/kitchen scrap bins with holes, and I’ll be filling borders as tightly as possible with sunflowers, marigold, aster, borage, yarrow, lavender, lemon balm, and chamomile

Hi Em.
I would first start by checking the season to sow some of your plants. Radish, turnips, lettuce, spinach, cilantro and most onions are cool season crops. In central NC all of these can be sowed now or at least started inside.
By the time you harvest the cool season crops you can be planting your favorite summer vegetables.
I would consider planting oregano in a pot and keep it harvested. It spreads pretty easily and may take up a whole square before long.
I’d start pepper plants inside soon. Peppers like poblanos take a longer season  you will have in western NC.
In the fall I would definitely sow Austrian winter pea for nitrogen fixation during the winter. Its natural lifespan doesn’t end in your location until June. If planting before then just chop and drop a week or two before planting. It’s such a great cover crop that it will keep the soil temp to low for direct sowing. That’s why it should be chopped and dropped a couple weeks before planting.