I had inserted only front part of my penis to a girl's vagina. Just I was pushing it in the first time she felt pain, so I took back out and again tried to insert it. Again there was pain, so I stopped. Is there any chance of pregnancy?
Let me be very clear. What you did is called fornication (or sexual immorality). You were engaged in having sex without being married. The fact that it was brief and that you did not to ejaculate doesn't change the fact that you were still having sex when you were not married. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4).
While the odds are small, the possibility does exist that you could have gotten her pregnant. When a man becomes sexually aroused, his body begins producing a fluid from two glands called the Cowper's glands. The purpose of this fluid, called "pre-cum" in slang, is to cleanse your urinary tract prior to intercourse (the acids in urine kill sperm). It also lubricates the urinary tract so that when you ejaculate the semen is able to shoot out, leaving very little behind. Depending on the man and his level of arousal, the quantity of pre-ejaculate fluid produced can be little or a lot. The excess fluid drips from the end of your penis and also provides a small amount of lubrication for intercourse. The fluid comes out long before you reach the point of ejaculation. Because of the way the male body is put together, small quantities of sperm can be present in this pre-ejaculate fluid.
It only takes one sperm meeting with one egg in a girl's body to produce a child. And, you must remember that sperm swim, so even if the fluid containing the sperm is deposited near the entrance of of a girl's vagina, it is possible for a sperm to swim up the vagina and reach an egg. However, in your case, your penis was well within her vagina with more than enough time for your pre-ejaculate fluid to be deposited in her vagina.
To give you an idea of the possibilities, a married couple trying to conceive a child have an 85% chance to become pregnant in a year's time frame. Or another way of looking at it, if 100 couples were trying to conceive, in one year 85 will have achieved their goal. The withdrawal method of contraception (where the man withdraws his penis before he ejaculates) lowers these odds to 19%. In other words, if 100 couples were using the withdrawal method to prevent conception, in one year 19 of the women would be pregnant anyway.
While the odds are low, it is not impossible that you might have gotten her pregnant when you sinned.