Casie, I am so sorry you went through that. I cannot imagine the pain you must be feeling. You're so young, you have your whole life ahead of you, dear. Please remember that Jesus loves you and if you have asked for forgiveness, he has already forgiven your sin.
True, you can never be a virgin again, but that doesn't mean you can't find happiness and joy. Most people (even the Christian ones), don't wait for marriage anymore. It's sad, but it shouldn't discourage you to try harder next time. Honestly, I would advise you to not go out with boys anytime soon. You've already had it and I can imagine it would be very difficult to stop now. So try to stay away from boys for a few years, if you really want to wait. I think you need to focus on yourself and your relationship with God for now.
I also recommend you read a book called "And the Bride Wore White" by Dannah Gresh. I read it and I think it's great. I especially like that she gives advice to those who have waited till marriage and those who have made the mistake of having premarital sex. Her book helped me realize I had a pride problem because I am a virgin. So even virgins are sinful people. And pride is just as bad of a sin as premarital sex...maybe even worse.
I think you would really like Dannah Gresh because she herself is open about the fact that she made the mistake of having premarital sex. She is now married to a great guy and has a beautiful family. I know that God can heal you and do the same for you.
Finally, I wanted to point out to you that none of us are pure. Only Christ is pure. We are all sinners like Moses, Jacob, David, Judas and Paul to name a few. Even Mary, Jesus' mother was a sinner. Don't think that just because someone is a virgin, they are pure. That's far from the truth. True purity is found only in the sinless and that's our Lord and Savior Jesus Christ.
I'll be praying for you, sister!