Frankly, if you had committed what the Bible calls the unforgivable sin, you wouldn't even be writing me, and you wouldn't even be wondering if your sin could be forgiven. Let me explain.
The reason I say this is because the Bible says only one sin can't be forgiven by God—and that is the sin of refusing His forgiveness. Let me explain it this way. When Jesus died on the cross, all our sins were placed on Him, and He took upon Himself the judgment we deserve. Now, God offers us salvation as a free gift—free, because Christ fully paid for it by His death for us. The Bible says, "For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord" (Romans 6:23).
But what if you refuse that gift? What if you turn your back on God's offer of salvation and refuse to have anything to do with Christ? What if the Holy Spirit convicts you of your sins and points you to Christ's forgiveness—but you turn your back on His witness and (in effect) call Him a liar? That—and that alone—is the unforgivable sin.
Don't carry your burden of sin and guilt any longer but hand it over to Christ and trust Him to take it. Confess your sins to Him, and trust Him to forgive and save you. And He will, because God loves you and wants you to be His child forever.