Egg whites are great, salsa on top or a little cheese is OK as well. Wheat bread is great as well - make sure whole wheat is used over buttertop wheat - its less processing.
You want to be drinking water throughout the day. The rule is if you feel thirsty, you are already slight dehydrated as that sensation lags a little bit. So urine color is usually "light lemonade" colored or closer to clear and you should be clearing roughly every couple of hours or so. This is just a guide so you know how much should be sipping during the day.
So for breakfast you're on the right track. Oatmeal is a great fibrous complex carbohydrate, you can add fruit if you want or a little brown sugar. You can also eat wheat bread for toast in place of oatmeal, with egg whites and a little cheese. Milk, OJ or water are great. I would advise against hot cocoa everyday only because its probably loaded with some processed sugar. So for breakfast a good choice would be a protein(like egg whites) a complex carb(oatmeal, whole toast) and then fruit of your choice.
Lunch is excellent, salads, anything with roughage, veggies, a lean protein like the chicken breast, turkey or some steak if you prefer some complex carb or starch like a pasta, whole grain bread with your sandwich if you go that route. You could also have a yogurt with lunch or a snack. The name of the game here is another well rounded meal, with complex carbohydrate.
A snack between lunch and dinner(or breakfast and lunch) could be a yogurt, fruit or veggies, some seeds or nuts.
With dinner its basically the last main meal of the day, where the body is getting ready to settle down for the day, preparing for sleep - so typically a smaller dinner is fine, especially if you are retiring early for the day. Assuming the little one isn't keeping you up, most people have a lesser need for macro energy later in the day. So a lean protein, any sort of vegetable you want and another complex carb like brown rice, sweet potato with salad.
Nobody says you need to stuff yourself or eat certain things just because its a certain time of the day. But an example of a well rounded meal would be a small portion of protein, a complex carb and then a vegetable or good salad with a lighter dressing.
So I can definitely be way more specific if you want on food amounts but the easiest way is going to be 4-6oz for a serving of lean protein(chicken, beef, fish) and then usually what the label calls for a serving of carbohydrate. The cool thing with fruits and veggies is that they are literally "nature's serving size" and like I say veggies can be eaten how you like, when you like, especially the colorful stuff.
Just let me know how you need your info.
..and just to let you know I am still sifting through tons of information on websites. If you are up for you I might just find single stuff and piece it together. Core execution is hard enough for some people, worse if bad habits are formed.