It’s true that spreading your meals out into 5-7 small meals throughout the day is good for your metabolism and can help with weight loss, assuming that you’re eating about the same amount of food as you would on a 3 meals/day plan. However…
It’s also advantageous to eat that many meals when your trying to gain weight, so that you’re body always has a ready supply of material with which to build muscle, and to cause it to never have to break down muscle for energy. It’s also easier to get more food down your throat if you break it out over many meals, rather than eating 3 massive meals.
In the case of breakfast, you haven’t eaten in about 8 hours, and your body does most of its muscle-building while you’re asleep. So you’re in a catabolic state and risk losing some of the muscle you’ve worked so hard to gain if you don’t eat soon. So as soon as you can after waking, you should eat a big breakfast of carbs and protein.
I’d also strongly suggest eating something before you go to bed, ideally something rich in casein, like cottage cheese and/or a Grow! shake.
In addition to adding this nighttime meal, I’d suggest replacing the skim milk with whole or 2% milk, or even chocolate, replace one of the tuna sandwiches with a peanut butter sandwich (with tons of PB), and add some calorically-dense snacks (e.g. nuts, raisins). You really should add a lot more than that, but these should be easy additions.