That's actually not too bad a start on your diet.

The biggest change I'd make is making sure you get at least 20 grams of protein every 3 hours or so.
Breakfast:
1 whole egg and 4 whites (scrambled with spinach and tomatos, maybe), 1/2 cup oats sweetened with berries
Snack:
Apple and protein shake (this would be a good post-workout snack if you need to move it)
Lunch:
Lean Turkey breast (make sure you're getting 20g of protein from meat) on whole wheat bread, non-fat mayo, mustard, half an avocado.
Snack:
Veggies or fruit
and tilapia (or tuna)
Dinner:
Chicken breast, lowfat bbq sauce, veggies, mashed potatoes (real ones)
Pre-bed snack: cottage cheese and some kind of nut/nut butter
As time goes on, you will probably find it beneficial to move to eating more and more whole foods. That means you'll need to find the whole food equivilant of your more processed proteins (lunch meat) and grains (bread...for now make sure "stone ground whole wheat flour" is the first ingredient in your bread, or look for a sprouted grain bread). When it's time for you to concentrate on leaning up again, start by easing out of anything that might have extra sugar you don't need (like bbq sauce, maybe your bread and possibly fruit later on down the line) and other empty calories (mashed potatos may be a culprit depending on how you flavor them). For now, though, I think your diet looks very balanced compared to a lot of people...you'll notice I didn't add anything new to your diet except tilapia as another protein source and nuts as a fat source. Aside from that, I just moved some things around. You've got what looks to be a good variety of food every day and a great handle on things already.
I'd start with aiming for a 40/40/20 (protein/carbs/fats) macro breakdown and see how things go from there. You'll want to eat at least your body weight in grams of protein (so if you're going to eat "too much" of something, eat too much protein), and really a gram and a half would be great. Enter what you eat into a site like fitday, using the nutrition data from the brands you actually buy as much as possible. If you need to adjust fats use foods like nuts, olive oil, avacado and fatty fish like salmon. If you need to adjust carbs, look toward fruits, sweet potatos, brown rice and oats (if you feel you need to remove carbs, I'd ditch fruit before grains). I think it's a lot easier to make adjustments based on whole foods because there aren't surprise sugars in fat sources or fats in carbohydrate sources. The only "surprise" you'll get is some bonus protein.