Am I stressing too much?

I had sex 2 weeks ago, and I got ewcm (indicating I was ovulating) about 4 days later. My period lasts about 7 days so I would’ve been ovulating on cycle day 11. My cycle is 27-29 days long. My partner used a condom and pulled out all together. I woke up around 8 today, got Starbucks and ate half a croissant but that was about 2 hours ago. I got home 20 minutes ago, laid down a bit, and when I got up I felt so nauseous. I felt like I had to throw up but it wouldn’t come out. I think I’m constipated but I had (tmi) almost diarrhea when I got home. I’ve been stressing for a week now about me being pregnant. Could I just be getting these symptoms because of stress? My period is due next Thursday.