Period scare

I’m 18 and I’m sexually active here and there with my boyfriend, we go back and forth usually using condoms and sometimes just the pull out method. My emotions have been all of over the place lately and I’m very stressed so I figured my period is coming, I also have tender breasts, and cramping here and there but my period is now two days late according to the flow app. On this app it’s telling me my period is to come in three days. I have always tried to be safe about sex, he has never ejaculated in me but I’m getting nervous about my period not coming ? Any advice