So you are claiming God's nature constrained him from making the bread and wine into His body and blood? Did he or did he not multiply the five loaves and two fish to feed the crowd of five thousand and afterwards have twelve baskets full remaining? How did he do it?
Was Jesus fully man ? Did Christ come down from heaven and become man? Do you believe that Christ was not completely man?
He had a human body and was willingly constrained by the limitations that all men have because of that body.
If Jesus multiplied His flesh it was a spiritual act and a spiritual reproduction of his flesh, it was not his actual flesh. He was wearing that flesh, that is the rub for you. If it was a spiritually produced flesh it was not his 'ACTUAL Flesh that would die on the cross.