If the dairy issue is lactose intolerance, are you sure you can't tolerate hard cheese? Most aged cheeses have almost no residual lactose. Cheddar works fine for me, and I can actually tolerate most low-moisture mozzarella too.
I thought I was just lactose intolerant, but it turns out I actually have multiple food intolerances and have to be pretty careful about what I eat. The diet that originally fixed my GI issues is called low-FODMAP, although it turns out I can tolerate a moderate amount of FODMAPS but not crazy amounts.
Anyway, I mention cheese because it helps me a lot with balancing snacks. I also need to be careful about my blood sugar and carbs, and as a result my diet is not always the most mustachian. For breakfast I usually have a lactose-free protein shake and some non-tropical fruit (apples, berries, citrus all are fine for my blood sugar). For lunch I have some sort of soup/stew with a combination of veggies/beans/meat. Afternoon snack is fruit and hard cheese. Dinner has a lot of variety, but tends toward beans, whole grains, some meat, and lots of veggies. Sometimes I'll have pasta, but I need to make sure it is a small portion balanced with a protein source like meatballs or sausage.
I keep snacks with me to combat low blood sugar, and if I'm low I'll have a "fast carb" snack (juice, fruit snacks) followed by a "slow carb/protein" snack (low sugar granola-ish bar, trail mix) once my blood sugar has come back up from the low if I'm not close to my next meal.
Finally, I would suggest a check up with your PCP, and an A1C test. Reactive hypoglycemia (what you are describing) can co-exist with pre-diabetes and Type 2 diabetes, although it's not super common. GI issues and fatigue also probably should be checked out by a doc.