What exercise is good for someone who is strong but has trouble getting big?

My genetics are for strength, not for size. It's obvious throughout my family members. What exercises and supplements/protein can I take in order to gain size also? I can get stronger but the size stays the same. The size I have now came from high school when i had just started out. I need to also lose weight but I think I can accomplish that by working out/playing sports every day.