My bf came in me 4 times a week later i got my period for only 4 days which isn't normal but breasts are really soar could i be pregnant

Maybe. Maybe not.: It can be hard to guess whether a woman is pregnant or not. A urine pregnancy test, done correctly, gives a reliable result 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after missing a period, or after having a "weird" period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and thus lead to a repeat test.

Unlikely: if you had your period at its normal expected time, even if it only lasts 4 days, it is really unlikely that you are pregnant. However if you do not get your period at the next month, take a pregnancy test. Sounds like you might also want to consider getting on a method of birth control.