I’m glad that in giving up “church” you did not give up “Christ.” I can tell by your concern about your salvation that you desire to know God and His salvation. There is a very simple solution to you confusion. Salvation is not in a prayer for God to save you. Salvation is putting your faith and truth in God; that is, in God’s Word; in what God has said; and that being, Jesus Christ died for your sins (for all your sins, for the penalty of all your sins) and that he was buried and that he rose from the dead for your justification.
From what you said, I think you know all this, but I think you are putting too much trust in your faith. There is nothing special about faith. Faith is just believing what someone said or did is true. Your faith is only as good as the trust-worthiness of the person you are putting your faith in. When your faith is in the Lord Jesus Christ or in what God said Jesus Christ did, then it is powerful in that you can trust God to be true.
Faith can be defined this way: Faith is taking God at his Word, and leaving the consequences rest on his faithfulness. I Corinthians 15:2 says you are saved if you believe verses 3 & 4. God said that. You know it is true because God said so. If you have decided to believe that, trust in the DBR of Jesus Christ for the full payment of your sins, God said you are saved. Now it depends on His faithfulness, not yours. The consequence of your salvation rests on his faithfulness. If he indeed cannot lie, then you are saved. If he can lie, and if Jesus Christ did not pay for all your sins, then you are not saved. The point is, your faith is only as good as the trustworthiness of the object of your faith. Don’t put faith in your faith, how much you believe, but in who and what you believe.
There is also a difference between being saved, security and assurance of your salvation. A person is saved when they trust the gospel (Ephesians 1:13; 2:8,9). They are secure in Christ by the sealing of the Holy Spirit whether they know it or not, according to Ephesians 1:13,14 as well as Romans 5:1,2; and 8:31-39. Assurance comes when you read these and all other gospel verses over and over, till the truth of those verses are confirmed in your conscience. Assurance seems to be your problem, not salvation. A person is saved when they believe the gospel. They are then secure whether they believe it or not and they are saved whether they have assurance or not; all because God will save them as He said he would, because He is faithful. I think this should help you.