Well lets make sure you and I are on the same Page here. I am posting God's Word which seems to me, ties the Feasts of the Lord, with His Sabbath, not with the Levitical Priesthood, since several of them were established before God's Covenant with Levi. This seems relevant to me.
And to be clear, I don't believe sacrifices ended, because Jesus didn't teach that. Even God's Sabbath is a sacrifice offered to God. A man that isn't willing to sacrifice all that he has, all that is most precious to him, like his pride, his religion, his family, his very life is not worthy of the Christ, at least according to Him. I can quote Him if you like, but I think you know the Scriptures well enough that you know where to find it.
Of course I don't continue to kill the Passover Lamb, as it was symbolic of the Christ, whose blood "(Life)" was to be spread in our works, our walk, and in our mind. (Two door posts and Lintel) Jesus Himself said,
17 And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves: 18 For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come. 19 And he took bread, and gave thanks, and brake it, and gave unto them, saying, This is my body which is given for you: this do in remembrance of me. 20 Likewise also the cup after supper, saying, This cup is the new testament in my blood, which is shed for you.
Clearly Jesus understood the Commandment to keep this day Holy, and even showed those who are seeking the Kingdom of God and HIS Righteousness how to do so, after HE became our Passover.
As for keeping them. For me, these are "Holy" days, like God's Sabbath. In my understanding they are kept, like God's Sabbath, from the heart. We found God's Instruction and have come to understand them. Passover is not a Sabbath, but the first day of unleavened bread is. If a person is seeking the Kingdom of God and HIS Righteousness, from the heart, HE will direct that man as well. This is my belief now for over 30 years and by reason of use, I have come to know why God created these days which HE esteemed above other days.
I think the first step is acknowledging the Scriptures regarding this topic to see if the religions of this world have it right. Clearly the philosophy that God's Holy Feasts, including His Sabbaths are not tied to the Levitical Priesthood. From there, at least a person knows who NOT to listen to.