Welcome to the board.
From your question, I suspect you might have become a catechumen a little too soon.
Let me explain: The idea of sin is of the essence to Judeo-Christianity. In fact, the whole point of Judaism---and, by extension, Christianity---is reconciliation with God. How did humanity become estranged from God? By putting its own will ahead of His: the sin of self-idolatry, pride. Instead of conforming ourselves to His will, in gratitude for the beautiful life He gave us, we decided to follow our own desires, to think first and foremost of ourselves. Thus, the allegory of Adam and Eve.
In other words, the largest problem we have to tackle when we become committed Christians, is to become obedient to His will, to subsume our wills to His. What do we get in return? Relationship with Him, His presence in our lives, His love:
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness and self-control. Against such things there is no law. 24 Those who belong to Christ Jesus have crucified the sinful nature with its passions and desires. 25 Since we live by the Spirit, let us keep in step with the Spirit.
Thus, the greatest saints and monks have always believed that sincere humility is the surest and most direct way to God. Humility is the exact opposite of pride; it is a kind of supreme selflessness, a discarding of one's ego in the trusting knowledge that God will guide our lives better than we could ever guide ourselves.
Christ Himself is the model:"Nevertheless, Your will, not mine." We aspire to be like Him.
The idea of sin you mention is more Calvinist than Orthodox, and it's misleading. Calvin believed humanity was evil and fatally damned. The Orthodox, OTOH, believe God loves
humanity or He would never have created it in the first place. Also that, He, in the person of Jesus Christ, came down to earth and told us everything we need to know about how to save our souls. But humans are imperfect. We need to put our egos down and vigorously empty ourselves of our own illusions in order for God to be able to work within us.
Not one of us is a sinless person; we are all vulnerable to pride, anger, sloth, despair, lust, etc.---sometimes several of these at the same time. That is all that is meant by sin: innate human frailty. It's also called, I believe, the Tragic View of life. I realize that modern education places a great deal of emphasis on "self-esteem," but this runs counter to the fundamental Christian worldview. The church does not intend for you to feel irremediably bad about yourself, but you are supposed to cultivate a healthy distrust of your motives and actions. Every day, we fall short of perfection--sometimes without even realizing it. That's what Forgiveness Vespers is all about. It's a chance to rectify hidden sins.
Lent is very beautiful in that it permits us to get back to basics once a year.
I came from agnosticism and Buddhism myself, and I know how some of that language can sometimes fall on the ear ("and in sin did my mother conceive me"). After a few years in the church, however, I came to realize how very true it is.
I'm sorry to state this, but if you are satisfied with your soul, feeling there is very little in yourself to improve upon, you are probably not going to enjoy being an Orthodox Christian. I might suggest taking it slow and easy until you know what you're committing yourself to.