Oh Alex, it's rather obvious that if God the Father is now speaking through His Son in these last days then the Son could not have spoken in the Old Testament as the angel of the Lord.
What you really have done is make your position even worse. At Hebrews 1:2 the Father appointed His Son as the heir of all things, and in fact "through" the Son and "by" the Son He made the world. I know specifically the word "by" is not there, but it there at John 1:3 and at Colossians 1:16.
At Hebrews 1:3 the Son is the exact representation of His Father's nature, and upholds all things by the word of His power. In continuing to read further in the chapter we come to vs6, "And when He again brings the first-born into the world, He says, "And let all the angels of God worship Him."
The obvious question that comes to mind or should be realized is the fact that Jesus is "NOT" an angel which I have trying to explain to you on numerous occasions. Then at vs8, But of the Son, the Father says, "Thy Throne O God is forever and ever.
Jumping to vs10 the Father says referring to His Son, "Thou, Lord, in the beginning didst lay the foundation of the earth, And the heavens are the works of Thy hands." This verse is completely "consistent" with John 1:3 and Colossians 1:15.
Now, getting back to you giving Zechariah 1:12-13! Do you really think that these verses are going to "negate" all that was said starting way back at Genesis through the Book of Zechariah? You keep saying that God spoke and not the angel of the Lord at Exodus 3:2-6.
Can you please tell me why the angle of the Lord is in the midst of the burning bush in the first place? What purpose does he serve? This in view of the fact that vs 4 says, "God called to him/Moses from the midst of the bush?
In any event, at Genesis 26:2-5, the Lord appeared to Isaac and tells him what land to live in. At vs3 God tells him, "I will establish the oath which I swore to your father Abraham."
Moving on to Genesis 31:11-13 we have the angel of God saying to Jacob in a dream. Vs12, And the angel of God said, "Lift up now, your eyes and see that all the male goats etc. And I have all that Laban has been doing to you.
Vs13, "I am the God of Bethel, where you anointed a pillar, where you made a vow to Me, now arise and leave the land, and return to the land of your birth."
Right here, as plain as day the angel of the Lord/God claimed He was the God of Bethel. This vow can be found at Genesis 28:13, "And behold, the Lord stood above it and said, "I am the Lord the God of your father Abraham and the God of Isaac; and the land on which you lie, I will give it to you and to your descendants."
The point of this exercise is to "again" show you that the angel of the Lord/God spoke in the burning bush and has been speaking as the God in all of these situations. Alex, you cannot be like the guy that whistles in the dark, hoping the dark will go away. I've presented nothing but Biblical facts. You have presented questions and have gone out of you way to "diminish" the identity of the angel of the Lord, it won't work.