We are glad that you have come seeking God's help and that you have confessed and forsaken your sins in the name of Jesus Christ. It is only through the precious name of Jesus that we can confidently come before God's throne. There is no other name by which we can be saved and have this access to God. Salvation comes by believing in Jesus Christ, acknowledging Him as Lord and Savior of our lives.
Firstly, be assured that God has already forgiven you and remitted your sins. It is written "If we confess our sins, he is faithful and righteous to forgive us the sins, and to cleanse us from all unrighteousness" (1 John 1:9 WEB). So do not be full of regret and self-hatred. We will now pray for you and encourage you, based on the word of God.
Heavenly Father, we thank You for Your unfailing love and forgiveness. We thank You that Callum has confessed his sins and acknowledged Jesus as Lord and Saviour. We ask that You will bestow on Him the gift of the Holy Spirit. In the name of Jesus, we bind every spirit of condemnation, regret and self-hatred. Help Callum to move past his past mistakes and sins, strengthen Him to live a life pleasing to you, and help Him to become the person you want Him to be.
Help Him to develop a plan of action that He can work on daily to achieve godliness. Give Him the grace and strength to follow through with this plan. Let Him be consistent and persistent in this pursuit. Help Him to live a life that is pleasing to You. Help Him to realize that he is now a new creature. Old things have passed away and behold everything has become new (2 Corinthians 5:17 WEB).
Callum, if you have not already, you need to have a plan of action for your daily Christian living. A plan that will help you focus on the word of God, on your personal relationship with God, on evangelizing others, on helping others, on Godly character, on loving others, etc. You can start by structuring your life around praying, fasting, and reading your Bible daily. Also, share your faith with others.
With regard to the wrongs you have done and the people you have wronged, knowingly or unknowingly, you should repent to them and to God. But for the ones you do not know, make an altar of prayer for God to heal the wounds of those you have wronged knowingly or unknowingly. Make restitution wherever it is necessary and possible. You have received forgiveness from God. You need to accept that forgiveness and also forgive yourself, regardless of whether others forgive you or not. God's forgiveness is the most important, since He is the one that we sin against.
Be encouraged by this quote, "To fall is human, to remain fallen is a choice." Get back up and move on. God is giving you another chance to get back on track with your life. Do not despise the grace of God (Galatians 2:21 WEB). Callum, receive God's unfailing love for you, because His mercies are new every morning, great is His faithfulness (Lamentations 3:22-23 WEB).