Actually, my middle name is Thomas. And I was brought up RC. Thankfully, I was given some of the "doubting" spirit- as Paul directed (search the scriptures, etc), and found that Catholic Dogmas are those of men. Your explanation of transubstantiation is convenient. So when Jesus said "This is my body" he was really meant "this is bread, but the substance of this bread is my body"? Unfortunately, the RCC has taken a beautiful metaphor ("I am the bread of life" - was his substance really bread?) and twisted it into a man-made dogma. Worse yet, the RCC proclaims an anathema (denies salvation)to anyone who claims otherwise!
We only follow His lead...
John 6 53 Jesus said to them, "Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you. 54 Whoever eats 19 my flesh and drinks my blood has eternal life, and I will raise him on the last day. 55 For my flesh is true food, and my blood is true drink. 56 Whoever eats my flesh and drinks my blood remains in me and I in him. 57 Just as the living Father sent me and I have life because of the Father, so also the one who feeds on me will have life because of me. 58 This is the bread that came down from heaven. Unlike your ancestors who ate and still died, whoever eats this bread will live forever."