To Atone or not to atone

I think atonement for past sins is possible, if you believe that it is possible. Im sure that I have made a mistake that I have regretted. It made me feel scared of what might happen to me in the future. I did not directly find atonement for that particular mistake, but i have done lots of good deeds since then, that maybe the lord will find it in his heart, if he has one, to forgive me.