[ears_to_hear]

Nope, she never sinned, though grace touched her life like none other.

Sin is described as violating the law,

54. Q. What is mortal sin?
A. Mortal sin is a grievous offense against the law of God.
57. Q. What is venial sin?
A. Venial sin is a slight offense against the law of Godin matters of less importance; or in matters of great importance it is an offence committed with out sufficient reflection or full consent of the will.

Your church teaches only Jesus "kept the law perfectly"

578 Jesus, Israel's Messiah and therefore the greatest in the kingdom of heaven, was to fulfill the Law by keeping it in its all embracing detail - according to his own words, down to "the least of these commandments".330 He is in fact the only one who could keep it perfectly.

So Mary could NOT have been sinless right?

[Campion]

Your church teaches only Jesus "kept the law perfectly"

I think you just found an error in the catechism.

(Congratulations!)

The citation for that sentence points to John 8:46, which could certainly be used as a prooftext for Christ's sinlessness, but not the idea that sinlessness is his exclusive prerogative.

[Pyro7480]

So Mary could NOT have been sinless right?

Read the sections in the Catechism on Mary.