The reason you don't know if you are saved, is because you don't believe what Gods has said -I believe that I am saved because I put my trust in Jesus to save me as the scripture states.
Am I absolutely certain that I am saved as a fact?
Definitely not, because my salvation is ultimately in the hands of the Lord Himself.
I live by faith in Jesus Christ not by some theological discourse that states I am secure because God is sovereign.
Calvinism teaches absolute assurance but how do you know that you, personally, are saved?
1 John 5:13: John writes so that those who believe in the name of the Son of God may know they have eternal life.
There you have it, Gods Word reveals why you don't know if you are saved. I know that I am saved, because God is not a liar. I have placed my trust in the Lord Jesus, I believe His promise to save me is not conditional on my ability to remain steadfast in the faith. Salvation is of the Lord, not of my good works.
I'm not sure why you're so obsessed with John Calvin, but I can assure you that John Calvin cannot save you, nor can any man or religion. I would encourage you to take Gods Word seriously, and avoid vain disputes.
2 Peter 1:10: Believers are commanded to make their calling and election sure.
Romans 8:16: The Spirit bears witness with our spirit that we are children of God.
The only way I could lose my salvation, would be if God turns out to be the biggest liar. Hell would freeze over before that ever happens.