Preeclampsia questions

Hey everyone, yesterday at my doctors appt I was told that I may have preeclampsia and that I may have to deliver my baby next week at 37 weeks..I’m confused because my blood pressure is usually very good or alittle low. The past two visits they said it was 140ish over 90. But any time I take it at work (I work in a doctors office) it has normal. I have taken it for two days and it’s been perfect. Has anyone else experienced this? They did find protein in my urine and want me to do a 24 hour urine collection and lab work. Has anyone else had preeclampsia but normal blood pressure???