I swear by eggs for breakfast, hot, protein packed, healthy and quick. My favourite is a mixed veg omelette, but I also went through a long scrambled eggs phase which takes about 30 seconds to cook - add a pinch of chilli flakes, some chopped spring onion and cheese (optional) to scrambled eggs, it's gorgeous.
I feel your pain OP. I have a 3 yr old who has woken 2-6 times a night every night for 3 yrs and it is gruelling now. SAHM here too. I find I have to refuel every couple of hours with mini meals almost to keep it together. But am also still bfing her and borderline underweight myself.
I try to think of snacks as being mini meals as it helps me make them more nourishing and I feel better when I eat better.
For eg I might have peanut butter & banana on toast/sandwich, or 1/4 can baked beans on piece toast or fried egg on piece toast, or apple with almonds and raisins, or dark chocolate with pecans and dates, or a bean dip with cucumber/ breadsticks/pepper strips etc, or porridge with chopped nuts and raisins and molasses on top.
I don't eat dairy any more, but cheese and oatcakes/crackers with cherry toms/cucumber/apple/grapes was another I used to have a lot.
Another one I like it to heat a frying pan and chuck in pumpkin & sunflower seeds and a splash of soy sauce. Toss them together over a low heat for a min or two until the sauce has reduced right off and the seeds are coated and sticky. Eat.
Hot food definitely helps perk me up, I love a soup lunch. I would definitely suggest packing it with lentils or beans for protein though (or meat if you are a meat eater). You could make a batch and then it's just a quick reheat at the time.
Eggs/beans/cheese on toast are also good quick lunches that give you a decent protein boost too.
Last nights leftovers are also great for decent lunches that only take a couple of mins to zap in the microwave. Curry/chilli esp good for this. Leftover risotto is gorgeous cold as a kind of rice salad. ACtually I have to confess to being v partial to a cold risotto sandwich
Remus could you take a flask of soup for your lunch? Or take the beany wrap filling in a tub and assemble at lunchtime? Hard boiled eggs? Egg sarnies? Peanut butter sarnie? Tub of nuts/dried fruit/dark chocolate chunks? A lentil salad? I got a lovely puy lentil & roasted veg salad from a Gordon Ramsey program a few years ago, it was basically a case of roast diced red pepper & courgettes until done, meanwhile boil up your puy lentils in veg stock and then drain and mix with generous olive oil, lemon juice, s&P, some chopped sundried tomatoes and plenty of chopped chives/basil and mix in the roasted veg. It keeps well and I've taken it as a sharing dish lots of times and it's always been popular.