I had severe OCD for five years. Let me tell you I suffered so much anxiety over losing my salvation. I still have high anxiety, but more along the lines of social anxiety.
In Matthew 21:28-31, Jesus tells a parable to the religious leaders (I think) and says it is better that a man to have first refuse to do God's will, but then does it than the one who says he will, but doesn't follow through with it. You say you're afraid that you won't be forgiven because you had been too rebellious. But that is exactly what Christ came to save you from. In John 3:16, Jesus says whoeverso believes on him shall not perish, but have everlasting life. If Jesus saved Saul, a persecutor of the Church, how much more then can you be assured that he can assure your salvation?
Keep in mind also Thomas who refused to believe Jesus had resurrected until he had seen and felt the wounds of Jesus. Of course he was forgiven.
I know it can be really hard to not latch on to a single line in the Bible and feel utterly condemned and unforgivable. I remember crying everyday wishing I had never been born because of a choice I had made and a passage I had read. But through it, I came to cherish the Gospel, and afterwards my OCD had greatly subsided (I'm not saying this will happen to you, but I barely have any compulsions now).
Prayers for you!