I've recently committed an act of fornication. I disobeyed my morals severely. I've prayed to God, admitted my sins, in hope for His forgiveness and restoration of faith within me. I feel used and worthless and certainly unworthy of God's love and of marriage in the future. I always hoped to save myself for marriage, but was caught off guard and was humbled. How should I face God, and wholly recommit to Him and repent? Have I lost all chances of entering Heaven? What should I do if God has punished me with the responsibilities of pregnancy? I do not believe in abortion, and don't want to sin any further. I am in need of advice and spiritual help.
I suspect that like many people you focused on not committing fornication, but gave little thought to the things that lead up to intercourse. You figured that as long as he didn't enter you, you hadn't committed that grave of a sin. What you didn't count on was the strength of your sexual desire once it was triggered. As things heated up you found it impossible to stop -- likely you gave no thought to stopping until after it was over. See: What types of touching are forbidden?
Whenever sex takes place, whether a pregnancy occurs is a matter of odds. Some things increase the odds, some things decrease the odds, but the chance of pregnancy is always there. If a child occurs and you are not able to care for the child, then have the child adopted by a family who can care for the child. At least turn some of your sorrow into joy for someone else.
I'm puzzled that you first say you have prayed, confessed your sins, and asked for forgiveness; yet, you later then ask how can you face God and repent of your sins. Either you have changed your mind about what you did or you did not. Either you are determined not to repeat this sin or you are not.
God promises forgiveness to those who will admit they have sinned and have repented. There is no sin that cannot be forgiven if it is repented of. It really comes down to whether you have faith and trust what God said. "If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness" (I John 1:9). If you are forgiven, then the sins you committed will not keep you out of heaven.