If I can still remember my sins, even if I have repented, does it mean I have not been forgiven?
I think that at some point or another, most of the members of The Church of Jesus Christ of Latter-day Saints have felt this way. Shame and guilt are soul-destroyers and together they tend to be tools that Satan uses to impede our progress.
When asked those questions, I usually responded by saying, “If you feel the Spirit—when you pray, read the scriptures, teach, testify, or at any other time—then that is your witness that you have been forgiven or, alternatively, that the cleansing process is taking place, for the Spirit cannot dwell in an unholy tabernacle” (see Alma 7:21). In most cases the cleansing process takes time because our change of heart takes time, but in the interim, we can proceed with the confidence that God approves of our progress as manifested by the presence of His Spirit.
Some people are harder on themselves than the Lord is. Of course, we must repent to be eligible for the cleansing and forgiving powers of the Atonement, but once we have repented, there is no such thing as a spotted repenter in God’s kingdom. There is no black mark on our right ankle that says “2008 sin” or brown stain behind our left ear that says “2010 trespass.” The Lord declared the comprehensive cleansing power of the Atonement when He said, “Though your sins be as scarlet, they shall be as white as snow” (Isaiah 1:18). That is the miracle of the Atonement of Jesus Christ.
Someone has suggested that when Satan reminds you of your past, just remind him of his future!
Hope this helps you realize that Heavenly Father and Jesus Christ are lovingly awaiting for you to see yourself as they see you.