birth control period question

i’ve been taking birth control pills for two months for the purpose of preventing pregnancy. it really hasn’t changed my periods much and I heard it’s supposed to - like I still get cramps and my period is no lighter or heavier than usual. is that normal? does this mean the birth control isn’t working? i’ve taken the pills literally perfectly - haven’t missed a pill by more than 3 minutes ever. just want to make sure this is normal.