Should I be worried?

So my period is a day late, but I have had the normal symptoms ( back pain, a need to eat, cramps, etc.) and I'm kinda worried. I've done sexual stuff with a guy about 6 days ago, but when he came, he came on my stomach. We also did sexual stuff about 4 days ago, but this time he didn't cum. At all. I talked to one of my friends and she told me that Ill be fine but I'm having doubts. I have also been under a lot of stress with finals. Should I be worried?