Our basic, fall-back meal is meat and two veggies, and sometimes it was just meat and a starch. Tonight: roast beef in the slow cooker with herbs de provence and salt, and then roasted red potatoes with more herbs de provence and salt, and roasted asparagus, squeeze some lemon juice on the asparagus, add more salt (yes, I do love salt) and it was done.
Roast a chicken, mashed potatoes with chicken stock (if you use storebought, buy Pacifica brand or check carefully for wheat/gluten), a green veggie. Makes good leftovers.
Filling starches: rice, quinoa, potatoes, sweet potatoes, plus there are other GF grains like millet, buckwheat if you want for hot cereal. But we mostly stick with rice and quinoa, they're easy and I don't have to learn too much that's new.
Eggs, if you tolerate them--hard-boiled, they're portable and filling and nutritious (eta: just re-read the list, ok, no eggs). Drumsticks. I find protein and fat filling, so that's why I'm listing them as my go-tos. Meatballs--I use a meatloaf-type recipe, bake them and then grab-and-go.
I use this recipe to marinade the drumsticks, and they're portable...http://www.3men.com/competition%20chicken.htm
I do it w/o soy sauce (which often has wheat in it, though there are some wheat-free ones if you read carefully). You can make a lot and freeze.
Coconut oil is a good fat, there are recipes in the Traditional Foods forum (surprisingly high % of people with food intolerances there) that are allergen friendly, search for high fat snacks or something like that in the thread title.
In terms of a multivit, do you have one that's no dairy/gluten/egg? If you don't, I'd get a Thorne Basic Nutrients multivit, sold lots of places online, it's a good source of folate (low folate is related to IgE allergies), good forms of various vitamins and minerals. And if you want more minerals, Thorne biomins or citramins are mineral supplements. B vits mostly pass through in breastmilk, most minerals generally don't but would be good support to you, since you just grew two babies.