No matter how many sins you have committed, no matter how many mistakes you have made, you still have a chance to improve yourself, to be better, to repent and seek Allah’s Forgiveness.
Do not see despair of the Mercy of Allah. Only He can forgive your sins.
The past is gone. Don’t worry about it. Live each moment to the fullest. Be productive, lead a purposeful life that is pleasing to Allah, our Creator. Allah will take care of the future, in sha Allah.