I'm not trying to change your thinking nor do I question your faith. Just trying to understand the basis for the theology of transubstantion. By the way, Hopkins is one of my favorite poets. I have used his poems as illustrations in the classes I teach.
It starts with the words of Jesus, then we trace it through St. Paul then toa whole line of what people actually taught from the end of the first century through.
Between the continuity of teaching (very important to me, and probably one of the biggest factors) and the eucharistic miracles, and some of my own personal experience which I will not get into here, with that being personal between me and God, I don't have any trouble with believing it.
Sing, my tongue,
The mystery of the glorious body,
And of the precious Blood,
Shed to save the world,
By the King of the nations,
The fruit of a noble womb.
Given to us, born for us,
From a stainless Virgin,
And having dwelt in the world,
Sowing the seed of the word,
He closed in a wonderful way,
The days of his habitation.
On the night of His last supper,
Reclining with His brothers,
The law having been fully observed
With legal foods,
He gives Himself as food with His
Own hands to the twelve.
The Word in Flesh makes true Bread
His Flesh with a word;
Wine becomes the Blood of Christ,
And if sense is deficient,
To confirm sincere hearts,
Faith alone suffices.
Then let us prostrate and
Venerate so great a Sacrament,
And let the old law yield
To the new rite;
Let faith stand forward to
Supply the defect of the senses.
To the Begetter and the Begotten,
Be praise and jubilation,
Health, honor, and strength,
And blessing too,
And let equal praise be to Him,
Who proceeds from Both.
Amen. Alleluia.