About a week ago I was fooling around with this boy and I gave him oral sex and swallowed his ejaculation, then we kissed and he gave me oral sex. Is there a possibility that his sperm could have traveled from my mouth to his and then into my vagina? Could I be pregnant? Also, before this we had sex, but he did not ejaculate inside me and it didn't last for long. Does this rule out pregnancy?
I will be waiting anxiously for your reply.
I debated about answering this question for a while because all the wrong questions are being asked. You are only worried whether you are going to be inconvenienced by a child being produced by your foolish behavior when so much more is at stake. What you did is called fornication in the Bible. It puts you in danger of going to hell for eternity just because you wanted a few moments of "fun." "Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God" (I Corinthians 6:9-10).
But in answer to your question, it just takes one sperm from a man reaching an egg that you release to cause you to become pregnant. It doesn't matter how the sperm gets there. The average man's semen contains about a half billion sperm in each ejaculation. So yes, it is possible, though the odds are low, that one or more sperm could have been transferred to your vagina.
In addition, since he had his penis in your vagina, he could have left sperm behind then even though he didn't ejaculate. The length of time he had his penis in you doesn't matter. When a man becomes sexually aroused, fluid drips through his penis that is called pre-ejaculate or pre-cum. That fluid can contain sperm and you can get pregnant from it. Again, the odds are low, but it is possible. Many years ago, I knew a teenager who became pregnant from just such an action.
But you aren't considering what is more likely -- you have a very high chance of catching or transmitting some disease. Most sexually transmitted diseases are transferred by skin-to-skin contact or through the transfer of fluids. You had both. It is very likely that you weren't the only girl this boy had his penis in, nor is it likely that you haven't been with other boys. That makes it likely that one or both of you already have a sexually transmitted disease and that you just exchanged your germs. Oral sex might lessen the chance of pregnancy, but it does nothing to prevent catching a disease.
Then there is the damage you are doing to your ability to relate to other people. Sex is not just a physical action. It binds two people together. But when you treat it casually as you are, it means you have broken the bonds too many times. One day you might want to join yourself to a man in marriage, but the odds are that the marriage will not last because you will not be able to bind your soul to your husband. Worse, it will even impact your ability to relate with Christ. "Do you not know that your bodies are members of Christ? Shall I then take the members of Christ and make them members of a harlot? Certainly not! Or do you not know that he who is joined to a harlot is one body with her? For "the two," He says, "shall become one flesh." But he who is joined to the Lord is one spirit with Him. Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body" (I Corinthians 6:15-18).
Even so, disease and pregnancy are relatively minor concerns. If you want to see heaven, you need to come out of your sinful lifestyle. Being a prostitute who gives her body away for free is not worth all the problems you are bringing upon yourself.