I feel your pain. I’m a vegetarian with migraine and belly issues.
It’s hard to find the “right” foods to eat

Yes. Been that way my whole life. All you can do is listen more carefully to your body. When you're craving certain things, you'll know. Otherwise, only consume things you're not allergic to.

Try nuts and seeds, which aren't mentioned above, unless you're allergic to them too.

Yes! I'm up against this very same thing, but am finally beginning to sort things out.

I don't have a compelling reason to avoid red meat, but my husband can't have it in his diet, and it's not like I'm going to cook it for just me. But it's okay, I get my iron from other sources: chicken, fish (yeah, yeah, I know fish is on your avoid list), eggs, legumes, nuts, and leafy green vegetables. I guess I could also supplement iron, if need be.

I've been told to avoid fish as well ... but don't notice that seafood presents any sort of real problem for me, so I eat it anyway. If I HAD to give it up, I suppose I would. I'm currently supplementing with Vascepa, a prescription-grade fish oil. I'm certain there are also quality non-seafood alternatives that you could supplement with.

I eat lots of fruits and veggies, no problem. I'm pretty sure you could too. Maybe just steer clear of the very fibrous ones. Asparagus is very fibrous, but that one makes your pee smell nasty, so best to avoid anyway. Hahahaha.

Obviously skip the dairy and citrus since you have allergies. Perhaps try some of the non-dairy alternatives. I make my lattes with organic almond milk. Costco's Kirkland brand is good. Also, have you tried A2 milk? I haven't yet, but I want to. Sprouts carries it. I've read that dairy allergies are often allergies to A1 protein. Since your dairy allergy isn't anaphylactic, you might dare to experiment on yourself. As far as the citrus, there's a world of non-citrus fruit for you to enjoy.

Ah, carbs ... I love me some carbs! But, as I'm genetically high-risk for both Type 2 diabetes and atherosclerosis, carbs were placed on my @#$% list. So I gave up simple white carbs. No white potatoes, no white rice, no gluten-based pasta, no popcorn huge sob, and no gluten-based bread sob. I still eat sweet potatoes (love them), brown and wild rice, Tinkyada brand brown rice pasta (legit tastes like the real deal ... I am not even kidding ... also available at Sprouts), and I cheat every now and then with organic popcorn. Also, a local pizzeria offers a worthwhile gluten-free pizza, so I treat myself to that every now and then.

Seriously, though, I feel your pain. If I avoided EVERYTHING I'd been told to avoid, there would be literally nothing for me to eat. I mean, don't eat gluten, don't eat sugar, don't eat dairy, don't eat GMOs, don't eat processed anything, maybe try cutting nightshades out of your diet, you should try eliminating salicylates in case you're reacting to those, and then, some of my health food nut friends start listing off organic brand names that they say are no bueno. Aaaaaaargh!

At a certain point, you just realize it's all quite ridiculous and make for yourself the best diet you can given your circumstances.

*Insert standard "I am not a doctor" medical disclaimer here.