Bumper cars while pregnant? Freaking out?!

I found it I was pregnant when I was about 6 weeks and 5 days along. The day before I found out, I went to a theme park and went on bumper cars. I didn't even remember until now when I came across an article and I'm reading horror stories about how I could have placenta abruption now and sometimes you don't even bleed, just have cramps and I've been having cramps all throughout my pregnancy (I just thought my period was going to come late) that I now thought was just my uterus stretching but sometimes they're really weird. I've been freaking out all night, crying, feeling like a terrible mother. I'm 8 weeks now and still have a few cramps sometimes and I don't have an ultrasound until next week. Has anyone done this? What should I do? :(