HI!
Your hairloss is almost certainly caused by hormones. Hair has a natural growth cycle, so that naturally some is falling out every day. When a big shift in hormones occurs (like a pregnancy, or starting pills) it synchronizes the cycle so that all the hair falls out at once. You won't go completely bald, and your hair will re-grow. There's not much you can do about it, except stay healthy, eat right and take good care of yourself and your remaining hair. If you are interested, there are lots of web pages about the hair growth cycle--here is one: http://www.pg.com/science/haircare/hair_twh_21.htm
Good luck!
Dr B