Searching for Forgivness

Searching for forgivness seems to be a fruitless task for me. It sounds very inappropriate to say that, I know, but I feel that even when I recieve the grace of God, and he forgives me, that I am not forgiven. When I say that I have not been forgiven, I mean by myself. Thats the problem that I have been having lately. I sin, and then I am so crushed by the fact that I wavered in my faith that I then cannot forgive myself for what I did. Its a difficult place to be in.