How do we know the Sacrament of Communion as practiced in the Catholic Church was instituted at the Last Supper?

Communion is a common practice in the Roman Catholic Church. The tradition has a long history. Jesus kept the Passover since He followed the law. But there are Jewish traditions during Passover where you drink four cups of wine, break the bread, cover the bread, and hide it. How do we know Jesus did not do that and that He is not teaching us to celebrate Passover, to remember Him? He breaks the bread and dips it, gives blessings, signs hymns, and so on could well be a one part of a longer ritual the Jews where doing at the time and today.