My bf came in me 6 days ago when chance of pregnancy on my calendar was high. Is there anything I can do now to prevent a possible pregnancy?

It's a bit late. There are several options for "emergency postcoital contraception " (Plan B pills, Ulipristal pills, a copper intrauterine device ...). but they all seem to lose their effectiveness if used after 5 days; it is usually recommended that they be used ASAP after unprotected intercourse and up to 5 days later only.