The short answer is no, there is not a very high chance of pregnancy if sperm touches the outside of the vagina. But why are you putting yourself at risk!? Since you are obviously concerned about getting pregnant, why do you think it's a good idea to be messing around with genital to genital contact WITHOUT a condom? The guy may not have been inside you this time, but guaranteed if you continue making out in this way, you will very likely get into a situation where you'll feel pressured to go all the way. When that happens, not only will you put yourself at a high risk for an unwanted pregnancy, you will also put yourself at risk for sexually transmitted diseases.
My best advice: You need to do a much better job of educating yourself about the risks of being sexually active. Otherwise, one thing is gonna lead to another and you're going to find yourself pregnant.
I suggest contacting your physician to discuss this question further, particularly if you are sexually active. While you can find lots of information online about reproductive health (including information about how to get pregnant and sexually-transmitted diseases), it's best that you explore this topic with your doctor in person. A doctor can help ensure that you receive accurate, evidence-based information, and provide advice specific to your individual health and well-being.
Thank you for asking, but please do follow up with a doctor before engaging in sexual activity of this nature.
The short answer is that there is not a high risk factor. It seems that you may have many more questions that you need answered regarding sexuality and mature relationships. Please consider having a consult with a professional or trusted adult, such as a school counselor, school nurse or a medical professional in your community. And if you are asking this question because you are involved in sexual activity that is non-consensual (you don't want to be involved) -please tell an adult who can get you help.
Thanks for writing-
Louise Sattler, NCSP
Nationally Certified School Psychologist