I did something that I don't even know if God can forgive me, but I have asked for forgiveness from the Almighty and have truly realized my mistakes. My girlfriend and I were just talking. We started playing a game of truth or dare. We had our tops on, I was just in my boxers, and she was putting on her pants. We started playing while dressed like that when I ejaculated on her between her legs. She was just a little bit soaked. Is it possible that she can get pregnant? I told her that we will get married one day, but not now because we are still young. I have prayed to God day and night that she doesn't get pregnant. I've promised my God never to get close with her again.
All sins are forgivable if the person committing the sin is willing to change his ways and ask God for forgiveness (II Corinthians 7:10-11; I John 1:9). What you and your girlfriend did was get involved in lewd behavior. "Let us walk properly, as in the day, not in revelry and drunkenness, not in lewdness and lust, not in strife and envy. But put on the Lord Jesus Christ, and make no provision for the flesh, to fulfill its lusts" (Romans 13:13-14). Lewdness is basically behaving like an animal with no thought of what may happen. It improper for both of you to expose yourselves even partially -- regardless of the game that you were playing. Nor was it proper for you to touched her in a sexual way. "Now concerning the things of which you wrote to me: It is good for a man not to touch a woman" (I Corinthians 7:1).
In regards to the possibility of having gotten your girlfriend pregnant, the odds are low, but not zero. Your sperm swim and I gather that you ejaculated by her vulva. Cloth is not a barrier to sperm. For sperm to survive the journey would not be high, but at the same time it would not be impossible. When your girlfriend has her next period, you will know she is not pregnant. If her period is delayed by more than two weeks, she should check to see if she is possibly pregnant.