MystyRock, it sounds like you and I have had a similar experience. I traveled a path a lot like yours. (Me: Christian, questioning-everything Christian, atheist, Christian who still asks a lot of questions).
As a pastor, if I notice someone who is not receiving communion, I only find it curious. No judgment, no condemnation, no pity, nothing more than curiosity. So if you want to attend, and choose not to receive communion, that's okay. Really.
If you want to receive communion, you are no more or less worthy to receive it than any of us. The meal is symbolism of a life, death and resurrection that has already taken place, and as a Christian, you have already received the benefits of communion. The meal is a way of participating with Christ in His new order of creation.
I'm certain that I'm reading more into what you said than you intended, but you asked if it is a sin not to "take" communion. There is nothing about communion to be "taken," only to be received. And the meal is only a means of participating in the gift that you, as a follower of Jesus, have already received.
Communion is special and beautiful, and shouldn't make anyone feel uncomfortable. But if you do, you are under no obligation. You may choose not to participate in the meal.
RE: 1 Cor 11:28-29, when Jesus offered the first meal, he offered it to Judas, who he knew was betraying him. In the 1 Cor passage, what does it mean to "discern the body"? And what is the judgment? The judgment of God? Of the community of faith? Of humans? Of self?
In 1 Cor 10:16-17, Paul has already referred to the Church as "the body." He'll do it again, and more in-depth, at 12:1231.
So what does it mean to discern the body? It means that we are called to recognize the communal significance of the meal, and that we mustn't receive it selfishly.
The Eucharist is not to be feared, but to be received with joyous gratitude. Should we "take" it in selfishness, we are casting judgment upon ourselves. But should we receive it as a community-shaping gift, which reminds us of the awesome self-sacrificial love of Jesus, we should feel nothing but joy and gratitude.