Hi po! Just wanna ask your opinion regarding my case.

My last period was May 3, so supposedly May 31 yung next since I'm usually regular, na dedelay lang ng 1-2 days. My bf and i had sex last May 28, with protection, and he did not ejaculate inside, pulled out way before he was finished kase ayaw nga namin e risk kahit may condom, it was also my safe day according to my calendar. But my period is 4 days delayed already. So should I be worried about being pregnant? And is it too early to take a pregnancy test?