Could I have gotten my girlfriend pregnant when my penis touched her vagina?

Answer:

The problem is that when a man is sexually aroused he drips pre-ejaculate fluid. That fluid can contain sperm. It only takes one sperm, which is able to swim, reaching the woman's egg to cause pregnancy. The odds are almost zero, but not absolutely zero.

But there is a far more important issue because it remains regardless of whether you are about to become a father or not. The problem is that you were doing things you should not have done. You had no business exposing your genitals to a woman you are not married to. Nor should you have been pressing up close to her in that naked state. In the Scriptures, your behavior is defined as lewdness and what going on in your mind was lust. "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).

You are like a person who says he is afraid of falling off a cliff but meanwhile walks along the edge. The fact is that sin is progressive. You convince yourself that nothing happened last time, so no harm should come if you do the same again. But it is rarely the same, each time you go a bit further and one day when you do put your penis in, you'll wonder how it happened because you did not intend for that to happen. But the will be a lie. A person who has no intentions to have sex doesn't play along the edge of sex.

Sex and everything that leads up to sex belongs only in marriage. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4).