You don't tell us what you're doing. If you are following a strength-building regimen as most athletes do, then you can expect little muscular growth, only increased strength and fitness. In order to gain size, you need to follow a different lifting regimen, a body-building type. However, you may be constrained by your muscular makeup. Those who have a preponderance of slow-twitch muscle fiber in their makeup may never attain great size. However, they can develop great strength and endurance.

If you are pushing heavier weights progressivley then thats fine. you can only gain 5 kilos a year at max. Also, make sure you are eating enough to get fat without training. Then use the energy in the gym.