As you already know, it's not normal dahil kayo na mismo nagsabi na low bp kayo at dehydrated. That's bad enough kahit hindi kayo pregnant. Research of ways to keep your bp up like bawal magpuyat, etc. or better yet, consult your OB kung may pwedeng inumin na vitamins, and syempre drink lots of fluids para di dehydrated.
Having low bp per se shouldn't be a problem lalo na at iyon ang normal sa inyo (90/60 is already the lowest within normal range), but the mere fact that you experience other symptoms like pagkahilo is already a sign that it's not okay.