You have started out well by seeing your physician and ruling-out many conditions that might be causing your symptoms. I'm certain you have heard the term "mental illness", but in reality there is no such thing, as all mental symptoms, such as those seen in GAD, have a physical origin.
There are a lot of tonics and remedies out there that claim to rid one of conditions such as GAD, but all they really do in mask the symptoms, and they really don't do that very well. The proven medical practices that really work are anti-depressants, therapy (such as cognitive behavioral therapy and mindfulness), exercise, and taking omega-3/fish oil. Stress hormones, such as cortisol, actually destroy brain cells in the hippocampus region of the brain. The four medical practices that I named, actually promote the growth of new brain cells in the hippocampus.
Your focusing on a better diet can certainly add to the benefits. Here are some dietary suggestions for you:
Foods to avoid would be:
too much salt (you only need between 1.5 to 3 teaspoons a day)
chili or spicy powders
refined sugar and wheat aka "gut glues" (baked goods, cakes, cookies, white bread, pasta, granola, muffins, etc)
refined soy (soy milk, tofu, soybean oil)
industrial seed oils (canola oil, rice bran oil etc)
dairy if lactose sensitive
too many legumes, nuts and seeds - avoid peanuts
Foods to eat (these contain GABA, theanine and tryptophan boosters):
Water (even the slightest dehydration triggers anxiety warning bells)
Low carbohydrate, alkaline-forming vegetables eg. asparagus, bamboo shoots, beets, bok choy, broccoli, brussel sprouts, cabbages, capsicum/bell peppers, carrots, celery, cauliflower, chard, chicory, choy sum, collards, cucumber, eggplant/aubergine, en choy, endive, escarole, gai lan, garlic, green beans, horseradish, Jerusalem artichokes, kale, kohlrabi, leeks, lettuce, New Zealand spinach, okra, onions, peas, pumpkin, radish, rutabagas, spinach, squash, sweet potatoes, tatsoi, turnips, and watercress.
Low carbohydrate, alkaline-forming fruits eaten “just ripe” are best for anxiety, such as apples, apricots, avocados, berries, cherries, coconut, currants, grapefruit, grapes, guavas, kiwi fruit, kumquats, lemons, limes, loquats, lychees, nectarines, oranges, passion fruit, peaches, pears, persimmons, rhubarb, sapotes, strawberries and tomatoes.
Nori (seaweed) is great for iodine and potassium, calcium, vitamins A, B1, C and E.
Lemon balm, rosemary, thyme and sage are natural anxiety and stress relievers in terms of herbs. Ginger for spices, and chamomile, lavender and dandelion in terms of edible flowers.
Mushrooms are great for B vitamins, selenium, copper, and potassium.
Meat with fat (not lean) and offal (livers!) are awesome for zinc, vitamin B12, selenium, phosphorus, niacin, vitamin B6, choline, riboflavin and iron. A number of forms of meat are also high in K2. Grass-fed is best.
Seafood provides high-quality protein, including oil-rich fish like salmon as great sources of Omega-3 oils as well as shellfish being particularly good for zinc.
Healthy fats and oils to use for cooking include avocado oil, butter, coconut oil, ghee, lard, macadamia oil, olive oil, schmaltz and tallow.
Bone broths (or soups with bones, especially marrow bones) are great for those suffering anxiety and from acid reflux, IBS, or FODMAPS intolerance. The glycine found in bone broths is an inhibitory neurotransmitter, meaning that it helps you relax and improves sleep quality.
Eggs provide several vitamins and minerals, including vitamina A, B, D and E, choline, iron, calcium, phosphorus and potassium. Especially high in Omega-3 fatty acids, they are an excellent source of energy for anxiety sufferers.
Raw, fermented, full-fat dairy is probably best, such as cultured butter, yogurt, kefir, clotted milk, and aged cheese (gouda, cheddar). Full-fat, organic dairy would be next best while avoiding homogenised milk if you can.
Fermented foods and drinks to try out are sauerkraut, kefir, kombucha, coconut yogurt and tempeh. While helping balance your gut flora, many fermented foods increase the amount of B vitamins present, which is especially beneficial to anxiety sufferers.
Some nuts and seeds that are good are almonds, brazil nuts, cashews, chia seeds, flax seeds, hazelnuts, macadamia nuts, pecans, pepitas, pine nuts, pistachios, poppy seeds, sesame seeds, sunflower seeds and walnuts.
I hope that these suggestions help.
The very best to you, MJ!... Chuck