how can i confirm my dog that it's a pitbull or pitbull mixed????

by richa sharma
(new delhi,india)

one of my aunt gifted me a dog..i just showed that dog to one of the dog specialists and he told that yes it's a pitbull terrier. the reason why he told this was his locking teeth and many others. so i just want to confirm that it's a pitbull or any other breed. some of the other specialties that i noticed was his energy, aggression, intelligence and his power to pull things.this all qualities are very much there in my dog.and i wanna tell that he's 3 months old.
i wanna ask some more qualities that"ll make confirm that it's a pitbull or any other pitbull.
thank you.