Good day to you,
I have a question to ask: I and my girlfriend went to my house. We started playing rough with each other, which led to kissing her and before I know it her clothes were off and mine also, but she was still in her pants. I ejaculated in between her legs, not directly in her vagina, because I shifted back when I noticed I was about to ejaculate. She's a virgin, but I'm scared. I don't want her to get pregnant. I know this is a great sin. Please help me.
From what I understand, you and your girlfriend were alone in your house and in the course of events she took off her top clothing and you took off all your clothing. After humping her, you ejaculated on her pants.
Your fear is focused on whether you got her pregnant, but the problems began long before your ejaculation. "For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, thefts, covetousness, wickedness, deceit, lewdness, an evil eye, blasphemy, pride, foolishness. All these evil things come from within and defile a man" (Mark 7:21-23). From your lust you began sexual touching, first excused by saying you were roughhousing with her, but it quickly became more than than. "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). Once you were sexually aroused, you stopped thinking clearly and started shedding your clothes. From there you went through the motions of sex, though you did not put your penis into her. "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).
Sperm can swim through cloth, so much would depend on what she was wearing and how thin the material was. The odds are that you did not get her pregnant, but when sexual acts are involved, you can never say for absolute certainty that it could never happen.
But there is something else you need to realize. Sin tends to be progressive. When you think you have gotten away with one sin, it is easy to tell yourself that you can do it again and expect the same results. However, the urge is to go a bit further. Soon it will be her in her underwear, then naked, then -- oops! -- your penis slipped in. You'll keep telling yourself it was an accident, that you never intended for it to go that far, but the progression continues.
If you are going to be serious about being a Christian, then you need to stop making provisions for sinning. Don't have girls over when no one is around. Don't bring a girl into your bedroom or go into her bedroom. Basically, realize that you are male and, thus, you cannot trust yourself to behave in sexual situations.