To understand who "my sheep" are, or to understand those "given" to Jesus by the Father, you must understand foreknowledge. We are elect or chosen according to the foreknowledge of the Father. God could foresee who would believe in Christ in time and chose these persons. They are the elect, they are the sheep given to Jesus. But a person must believe for God to foresee it.
Jn 10:27 My sheep hear my voice, and I know them, and they follow me.
Notice the order in this verse, it is very important. The sheep #1 hear God's word, and then #2 Jesus knows them.
God does not know us in an intimate, personal way until we believe. He knows those that "hear". This is foreknowledge of who will believe.
Gal 4:9 But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage?
Notice the word "NOW" it is very important. God does not know us in a personal, intimate way until we believe in time.
However, God was able to foresee this future faith, and he could know this personal relationship in time before it occured.
Foreknowledge does not determine who will believe or who will not, it only foresees what will actually occur.
Those who God foresaw would believe are his sheep, and it is these believers that the Father gives to the Son.
I understand you will disagree as will most on the forum, however in Rom 8:29 he did foreknow, means just that. The people he had known before and the word of God tells us who that is in Amos 3:1,2
Hear this word that the LORD hath spoken against you, O children of Israel, against the whole family which I brought up from the land of Egypt, saying,
You only have I known of all the families of the earth: therefore I will punish you for all your iniquities.
In Hosea chapter 1 we learn this flock was divided into two fold. One of which would be in the land when the Messiah came and the other scattered over all the earth with the remembrance of them to cease from among men. Deut. 32:26. That could not have referred to the fold known as Jews for the whole world knows who they are and most hate them. Therefore it must refer to the fold scattered among the nations (Gentiles) and known as Gentiles (nations). In chapter 3 of Jeremiah we learn God had given a bill of divorce to this fold and he was showing them as an example to the other fold Judah who in chapter four god told they needed to take away the foreskin of their heart. Judah had been calling these people Uncircumcision (foreskins)
(castaways) thus the reference in Eph. 2:11,12 Wherefore remember, that ye [being] in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands; That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world: (God had given them a bill of divorce)
Foreknowledge twice in KJV. Once in the reference of the death of Christ slain. Duh! The Lamb slain from the foundation of the world.
The other 1 Peter 1;2 which is the very people shown above see verse 1.
However as you stated in your post even all of those are not called at this time. God is taking out a people for his name for a specific purpose, a remnant according to the election of
grace
He elects them as priests and kings and tells them:
having made known to us the secret of His will, according to His good pleasure, that He purposed in Himself, in regard to the dispensation of the fulness of the times, to bring into one the whole in the Christ, both the things in the heavens, and the things upon the earth -- in him;
See Acts 15:14,16,17,18 Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name. After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up: That the residue of men might seek after the Lord,
and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things. Known unto God are all his works from the beginning of the world.
Notice it is the Lord
and those upon whom his name is called that the residue of men seek. The same thing is stated in Joel 2:32 following what was quoted of Joel 2 in Acts 2.