Hypertension while pregnant?

I'm 30 weeks pregnant and I saw my doctor yesterday.They said I had high blood pressure and I told them that I had high blood pressure a month ago at my other doctors office and they didn't seem to say anything about it there.They told me that I should watch my blood pressure and that if I get a headache that doesn't go away that I need to call to go in.Well I don't have a headache but I feel a little light-headed.Its messing with my eyes.They feel weird everytime I look around and stuff.Should I call my doctors office?I am supossed to go see my doctor again on monday.Do you think I could wait it out and see if anything else happens?They told me that I may have hypertension so I don't really know what that could mean either.What does that mean?Thank you everyone.