late period.......

So I've only been sexually actice for about a month now and I've had my period once in the middle of it. My "friend" usually goes in raw for a little bit before putting a condom on. And last week he kinda went raw for longer than usual but he didn't cum until after he put on a condom and he even pulled out. I'm now about 5 days late on my period and I'm starting to get really nervous. A girl friend told me it might just be my cycle adjusting to me being sexually active. Another friend told me not to stress it because the stress might hold it back. I'm terrified because I'm just 18 and this boy isn't my boyfriend. I just need some reassureance to calm me down. Someone help please 🆘