If your blood pressure is normal, then right now it is technically not preeclampsia. (Criteria for preeclampsia diagnosis is 2 readings of 140/90 and 300 mg of protein or more in a 24 hour urine test.)
It is relatively rare for preeclampsia to develop before 24 weeks but it CAN and does happen. I was diagnosed at 23 wks and 2 days and had been having symptoms for a few weeks prior. We have someone here who had it at 18 weeks (which is extremely rare).
How is your swelling?
I think right now it is probably a good thing that they are looking into kidney issues and they should definitely keep a close eye on you. If you haven't been referred to a MFM (maternal fetal medicine specialist) I would request a referral, since they are the experts for high risk pregnancies.
900 mg is high enough to be considered preeclampsia with high blood pressures but protein levels can go up to the thousands and while not be great, be okay with close monitoring.
Me (29) DH (30)
#1-Olivia Caetlyn-9-28-09-9-28-09, 23+2 wks, emergency classic c-section, class I HELLP, IUGR
#2- Lucas Oliver (rainbow baby)- April 2011, 36+2 wks, HELLP and pre-e free! (lovenox and LDA pregnancy)
#3-Matthew, late October 2012...mostly normal, 37 wks, (lovenox and LDA again)
My blog: http://www.butterflies-and-rainbows.blogspot.com/