I am 15. What are the chances I may become pregnant?

Ok, I got my period on the fourth of June. The last time I got my period was 22 days ago. On June 4th until June 7th, I had unprotected sexual intercourse with my boyfriend, with him coming inside. My period suddenly ended on the 7th. Making it only lasting 3 days. Now, I know sperm can live in my system for quite a while. So, is there a chance I can become pregnant? Should I take a pregnancy test in 2–3 weeks, or wait longer, or shorter? What do you think the chances are? Please help me. Any input would be fantastic ! Thank so much ~!