Hi, Im 17 And Im Currently 14 Weeks Pregnant And

Hi, im 17 and im currently 14 weeks pregnant and I notice at my OBGYN that my blood pressure has been very low im also underweight being 5'1 and 96lbs I haven't put weight on my time of being pregnant and its seems that if im on my feet or moving around to much I get extremely light headed/faintness to were my legs feel like jello and goes out on me and I normally start puking? Is this normal?