We are interpreting Revelation differently. There is only one place where a millennium is mentioned.
(Revelation 20:1-3)
Then I saw an angel coming down from heaven with the key to the bottomless pit and a heavy chain in his hand. He seized the dragon—that old serpent, who is the devil, Satan—and bound him in chains for a thousand years. The angel threw him into the bottomless pit, which he then shut and locked so Satan could not deceive the nations anymore until the thousand years were finished. Afterward he must be released for a little while.
The 1000 years is not a unique reign of Christ on earth where Jesus then goes back to heaven and Satan is released.
The 1000 years is a limited timeframe where Satan is not allowed to deceive the nations to be fully antichrist. We,the church, are presently in this 1000 year binding of Satan as God protects us in the wilderness.
(Revelation 12:6)
And the woman fled into the wilderness, where God had prepared a place to care for her for 1,260 days.
In Revelation, John is using apocalyptic language. He is not speaking with exact literal language. Like Matthew, in the 1st chapter of his gospel and Daniel in his 12th chapter, John is choosing numbers that have general meaning, not literal meaning. (To be honest, this was the hardest thing to wrap my mind around when moving away from dispensationalist futurism. Numbers have different meaning in Revelation that express general lengths of time or various perfections. John is employing a numeric technique that is very common to apocalyptic language.
Ultimately the idea that our King would come in full glory, reign for only 1000 years, and then let Satan reek havoc on the earth again seems bizarre and terribly random based on three verses. It doesn't make any sense. But, when we understand that God is protecting his church so it can grow from a mustard seed to a tree by keeping Satan bound for a period of time, then these verses make sense. The early church would have rejoiced in knowing that their endurance was not in vain and that Satan was being bound. We, today, can also rejoice that Satan is presently bound and that we are marked by God.
I'm not a premillennialist primarily because of Revelation 20. I am a premillennialist mostly because I believe in the earthly fulfillment of unconditional promises made to Israel, which I know is an area of disagreement between us.
As far as the thousand years go, I don't think it has to be exactly one thousand years (although it could be).