"Now when [Jesus] was asked by the Pharisees when the kingdom of God would come, He answered them and said, 'The kingdom of God does not come with observation; nor will they say, "See here!" or "See there!" For indeed, the kingdom of God is within [or among] you.' "
In brief, the kingdom of God is wherever Jesus Christ is, covenantally-expressed. This is more than simply His omnipresence, by the Spirit. It is also more than His locative position in heaven, where His glorified body and blood is. It is also much more than a supposed future "kingdom" on earth. The kingdom of God is now--wherever Jesus Christ is glorified in His church: in the individual expression of particular saints; and in the corporate worship of the body of Christ.
Be thankful that the King of the kingdom makes all the difference. The kingdom of God is "within" you, or "among" you--if Jesus is truly yours.
[Puritan quote of the day: "Keep conscience clear and clean from secret sins. With what face can we go to a friend to whom we have given any secret affront? And will you be so bold as to come before the God of heaven when He knows you maintain some secret sin in your hearts?" --Samuel Lee, in "Secret Prayer Successfully Managed"]