[alnick]

Though sinless, she certainly experienced conflicts with those who were not, felt righteous anger, sadness, and joy. She is, after all, human.

According to Romans 3:23, Mary was not sinless.

Romans 3:23: For all have sinned, and come short of the glory of God.

Yes, she was human, which indicates that she was indeed a sinner, as are/were all humans, with the exception of Jesus Christ.

[Antoninus]

Yes, she was human, which indicates that she was indeed a sinner, as are/were all humans, with the exception of Jesus Christ.

Personally, I'll take St. Augustine's opinion over yours:

In refuting Pelagius, St. Augustine declares that all the just have truly known of sin 'except the Holy Virgin Mary, of whom, for the honour of the Lord, I will have no question whatever where sin is concerned" (De naturâ et gratiâ 36).

Heck, even another Augustinian, Martin Luther--the inventor of sola scriptura, himself--was closer to the truth on this matter than you are.

[Campion]

Yes, she was human, which indicates that she was indeed a sinner

This is very bad anthropology, because it equates sin with human nature. Sin degrades and dehumanizes human nature; it does not define it. When we sin, we don't "become human" or "become more human," we become, strictly speaking, less than human, and closer to the animal.