A little anxious about the possibility of pregnancy. Advice appreciated.

So me and a girl had sex on the 28th. Her last period started on sept 6, so we did it on the 23rd day of her cycle. She told me she ovulated about two weeks previous, but obviously you can never be sure. When we had sex, I pulled out well before ejaculating. She finished me in her mouth and swallowed, and I wiped myself off. We started kissing and stuff again and ended up having sex again about 5 or so minutes after the first time. I did not cum the second time. Now I'm concerned because it's now 4 days later and she hasn't started her period. According to the start of her last period, this would make the 27th day of her cycle.

She said her stomach has been hurting all week, and she's definitely had a few mood swings. That made me think her period was coming at first but tomorrow will be day 28 and so far there's been nothing.

So now I'm kind of panicking. I'm wondering what the chances here are and would love some advice. Thank you in advance.