I'm really scared. I commited a sin without knowing it at first. A while ago, when I was with my girlfriend alone, I touched her private parts and we had oral sex. A couple of days ago I asked her why she hadn't touched my private parts recently. I kept nagging her to find out why, but after reading some things on your site, I don't want her to touch it anymore.
What I actually want to know is if we committed a sin by doing all this. I never intended to hurt her. Now I'm scared I hurt her in the worst way possible.
I don't know which disappoints me more: the fact that you played around with sex or that you really didn't realize it was wrong.
I suspect that you did know that what you did was wrong. Perhaps not why it was wrong, but you did understand enough that you did this in secret. You even refer to your genitals and hers as your "private parts," so you know that they weren't for everyday exposing. "Can anyone hide himself in secret places, so I shall not see him?" says the LORD; "Do I not fill heaven and earth?"" says the LORD" (Jeremiah 23:24).
Was what you did a sin? Absolutely! Your lack of understanding doesn't turn a wrong into a right. For example, if you drove through a red-light, you would not tell the policeman that you didn't realize that a red light meant "stop." You would still get a ticket.
Nor does your intentions change what you did. If you threw a ball and broke a window, your parents might go a little easier on you if they agree that you didn't intend to break the window. However, the window is still broken and it still remains your fault.
What you did with your girlfriend is called "fornication." "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). I'm glad you now realize that it was wrong to do. Apologize to her and to God. Then start treating your girlfriend with respect.
Thanks for taking the time to help me. I really appreciate it.
Just one more question: I love to cuddle with my girlfriend and to make out with her. I was just wondering if this is a sin as well. Is it wrong to sleep in the same bed but have no sex or touch her private parts -- just cuddling and sleeping?
How do you think you ended up committing fornication the last time? What you are trying to do is see how close you can get to fornication without technically committing it again. See: How much sexual stuff is too much?
If you don't want to sin, you stay away from it.