Am i a campbell PLZZZ HELLLLP?

My last name is campbell and my dad is a campbell and my Grand father is a Campbell. We are all scotch irish and i wanna know if im in the campbell clan because we go to the tartan day parade and im in it and i walk with the campbells but ....... im a a reel Campbell or are there mor then 1 campbell family and if their are how can i find out witch one i bilong in? plz help me