Personally I think you shouldn't be asking on a forum if it's possible to be pregnant. You know what happened and if you are worried you are pregnant, then go find out form a professional, or something more expensive and descreet.. A test. (First response, etc)
I am pregnant... I am 15 years old and I am going to have to have an abortion.
This type of thing is very serious. Don't ask a bunch of strangers, it's your life,
do something that's more reliable, k?
Good luck.