Hello,
I am RN not MD:
If you are not married and going to be with one partner then it is best to practice safe sex. Which also means, "If its wet, and not yours, don't touch it."
I think you are asking if you will be safe from contracting a sexually transmitted disease. To protect the both of you ejaculate into a condom and not on her, wash your hands with warm water and soap for 2-3 minutes after being intimate with her and before you touch yourself or anything else. I am not a promoter of childhood/teen sex, but you must remain safe if your will is not strong enough to avoid the natural feelings of life. You should also read some books about sexually transmitted disease prevention (take a good long look at the deformities they cause on your penis and other areas of your body) and if your still not going to stop you should read some books or look up on the internet about becoming a father.
There are free clinics that are private that will test you for STD's. Go there and get educated before you become part of the problem.
No think your quite safe and so is she/her, we know sperm can travel but it needs a nice moist area to do that.
Good Luck
I think you're okay until your penis gets right near or into her vagina :-)