In all honesty I don’t mean this in a snide way, but I do think it would be more fruitful if you researched the Catholic and Orthodox understanding of the Eucharist before you try to “debate” it. That would save much time, and if you still don’t agree, at least you wouldn’t have to ask “catch-up” questions about the the one of the oldest Christian traditions on the planet. After all, only baptism is older for us Christians (and that’s only because it predates Christianity as we understand it).