High blood pressure and keeping an eye for preeclampsia symptoms

Hi, I’m 35 weeks pregnant. At a growth scan last week my blood pressure went about 140/90 but by the end of my appointment it came back down. I had been monitoring it over the weekend. Went to work as a teacher on Monday and knew when I came home I was exhausted and pale and blood pressure spiked to 150/99. I booked into my gp the next morning to get an official reading and they sent me to triage. In triage they checked my urine and took bloods but baby met criteria and my blood pressure came back down within the hour. They have told me to keep an eye for visual disturbances. Now my mind is in overdrive. Are these visual changes subtle or will I stop on my tracks when I have them.