. . . . “Bread” refers to a certain arrangement of atoms and molecules that form some stuff we like to eat and derive certain nutritional benefits from.
There is a huge difference in how you and I conceptualize reality.
For me, bread does not refer to just a certain arrangement of particles.
When I assert this it isn’t from some airy-fairy philosophical notions, but from the basic day to day living that you seem to acknowledge above.
God created and maintains the physical universe, so it is His Word that is the ultimate reality.
Jesus said “This is my body.” That makes it His body.
However, else your senses, their extensions in the form of scientific instruments and your world view puts it together, His statement makes it so.
You are overthinking the matter, using the concepts that you’ve been taught in science class.
You won’t get far that way in areas that don’t have to do with science. And, most of life has little to do with science.
Treat your love-interest as a collection of molecules and see where that gets you.
You will have to broaden your understanding, otherwise it will all seem absurd.
That’s my answer. Hopefully, it helps.