Unprotected sex last feb 6/7 withdrawal we washed after every round. boobs hurt. brown stain 6 days after. last period started jan 20. am i pregnant?

Unprotected Sex: Any time you have unprotected sex you are at risk for pregnancy. If you have missed a period get a home pregnancy test and check about 4-5 days after you miss. Likewise if your period is different check a pregnancy test. If you don't want to be pregnant get on a reliable form of birth control.

Could be pregnant: If your periods are regular ("28 days") based on 1st day of cycle Jan 20, your most fertile days would have been Feb 1 to 5. Your period would liklely have been Feb 17. If you did not use contraception (condoms, spermicide,etc) you could be pregnant. Check a home pregnancy test , or see your regular MD.