How did you know you had preeclampsia?

I know the obvious stuff like high blood pressure, but I was curious because I’ve been seeing spots and blurred vision very often the past couple days and I usually feel dizzy and shakey when it happens too. It’s not when I’m hungry, or been working hard on something. It happens just whenever and it has me concerned. My blood pressure has been very good this pregnancy and I’m just wondering if blurred vision was your first idea that you might have preeclampsia? I’m 28 weeks and concerned. Thanks!