Study Daniel carefully and prayerfully, especially Chapter 9. The tribulation is Israel's seventieth week. Not a five-minute job. (You have to back and forth in time and God's Word - I've been at it 40+ years and nobodys paid me anything I just asked the Lord (not man) to show me the truth.) Also, a careful and prayerful combing through the Book of Revelation reveals seven years in exact recounting of "days, months, years, and 'times'."
As far as the Day of the Lord, the purpose is revealed in Daniel:
to finish the transgression, and
to make an end of sins, and
to make reconciliation for iniquity, and
to bring in everlasting righteousness, and
to seal up the vision and prophecy, and
to anoint the most Holy. Daniel 9:24
The Book of Revelation unveils the spiritual warfare that begins the Day of the Lord. The Day of the Lord is when God Himself takes charge. Before He comes to rule as the King of Kings and Lord of Lords, Hes going to clear the decks, so to speak. He will utterly destroy the false Babylonian World System and all that adhere to it in defiance of His Kingdom come.
Hmmm...While I agree that the 70th week happenings are as you listed them, I don't think there is any "7 year tribulation" to be found there. IMHO, the book of Revelation is sort of a "tower of truth"; an ascending picture of what is going to happen - as one ascends higher and higher towards the top of the tower ones view grows wider and wider over the landscape. When one reaches the top one will see the whole view - chapter 21-22, which completes the picture one sees as one ascends. Does that make any sense?