Try the Catechism of the Catholic Church.
Bishops and priests, and even Cardinals, can depart from defined Catholic teaching.
The perennial teaching of the Church has been that conscience must be informed. And, in fact, that human conscience is open to influence from the devil.
Conscience may be important in the person’s actual culpability. But that doesn’t mean that the actions are right.
In this case, the OP is aware of the church teaching that contraception is wrong. If someone is telling them that they should ramain ignorant to the teachings of the Church and trust their (unformed) conscience, then that in itself could be wrong.
The only answer to the OP’s question is, yes, it is wrong to make use of contraception if they are aware of Church teaching and trying to live as a Catholic, in one mind with the church.