Sports nutrition is not only about eating the "right foods." When you eat and how is also important to improving sports performance. Muscle growth is tied to levels of insulin. To keep insulin levels constant, you should eat 5 or 6 times a day instead of the usual 3 meals. This avoids the roller coaster affect.
Also understand that after a heavy workout, you should first rehydrate, then within an hour eat a carbohydrate/ protein meal. Your body can replenish, and thus build and recover, faster at this critical time.
To make gains, you need to give your body the right materials at the right time.
If interested, I have posted on our website a free list of high nutrition foods that you can download and use to shop and plan meals.
Remember that being an elite athlete requires committment.