Could I be pregnant

Me and my boyfriend had sex on the 8th. It was the first time since before my last period. We used a condom but before he went in with out one just for a second and came out he says there wasn't enought time for any pre cum to get inside of me because he was barely even in me. The condom didn't break and we water tested it. I'm late on my period and I'm freaking out is there anyway I could be pregnant? I started my period on the 17 of last month but it's always been anywhere from the 21-25 when starting. I did have one if the symptoms when I'm about to start my period which tender breast. Also could stress have delayed it? I heard it can and I have a lot of stress with what's going on around me. Maybe I'm just being paranoid but any ideas?