Either the gates of hell shall prevail against the Church, or they shall not. If one must rely on scripture alone, it is clear that Christ declared His Church to be indefectible. Forever. The seed of doubt regarding one aspect of the Church, once planted, can blossom into doubts regarding other aspects of the Church. There is one, in the spiritual realm, who sows these seeds. In His parable of the wheat and the tares, Christ portrayed this individual as “an enemy.”
You might consider: How come the scriptures do not explicitly state that the Godhead is three eternal and divine Persons? That is the very basis, the foundation of our beliefs. Isn’t that a rather glaring error? Oh, you can argue the Trinity from scripture, but it’s simply not explicit in there. We have to trust extra-biblical revelation and the leading of the Holy Spirit on that, and many, many other doctrines.
One must consider doctrinal development, in which revelation refines, completes, fulfills what has gone before. Many, including myself, have had difficulties with Marian doctrine. No more! Time spent before our Lord in the Blessed Sacrament revealed the truth to me on a personal level.
And there will be found at least a major part of your solution. Go to Christ and ask Him about His mother. Read Revelation 12. Understand that Christ created His own mother and that she, bearing the only Son in her womb, is at enmity with the evil one. Enmity: having zero, nothing, to do with the other. As the devil emptied himself of all goodness that he was created with, so also Mary retained all of the goodness that she was created with, by her simple and unquestioning “Fiat” to Gabriel, who spoke directly for God.
As evil and detestable as the devil sounds (and is), the exact converse is attributed to Christ’s self-chosen mother. The devil has been described as “the nothing” and to properly understand the mother of our Lord, it is fitting and correct to assign to her each and every title in the Litany of the Blessed Mother.
Church teaching on Mary may strike us as hyperbole, even fantasy, but what we are actually considering here is not ink on paper, or the decision of gray-haired men in council, but the incomprehensible work of God as revealed to mankind through Christ’s indefectible Church. Mary is the most perfect human being ever created, because she was created (with all foreknowledge) specifically by Christ give her flesh to Him.
You might be experiencing a crisis of faith. That is extremely common, as we are relentlessly attacked in the spiritual realm. To counter that, we must employ the three theological virtues of faith, hope and love. All three are supplied, in overflowing excess, before our Lord Jesus Christ hanging on the cross, but on a perhaps more personal level, at adoration of the Most Blessed Sacrament.
Go there and express your doubts. Then, be as patient with our Lord as He has been with you. When you receive your consolation via the Holy Spirit, you will be changed.