What are the chances I'm pregnant if we had and he did not inside?

Last night me and my boyfriend had . I didn't think I was ovulating until next week, but this morning I went to the bathroom and when i went to wipe myself there was the mucus substance on the tissue. Though yesterday this was not the case. We had for about ten minutes but no condom, I don't take birth control pills but he did not inside of me. He only d after about ten minutes of me giving him a hand job AFTER the . I am aware of pre-c*m and that it contains sperm. What are my chances of being pregnant? And how can I tell this early on? Should I start using pregnancy tests now? I need to know asap. I'm only sixteen. I know it was unwise and stupid to have but we did so please anyone give me some answers and advice? Thanks...