placenta abruption

The u/s that I had today suggested that my placenta is slightly (just a small section) covering my cervix (partial placenta previa), and that as a result, it has started to pull away from the uterine wall near the cervix.  Thus, there is a small tear (or placental abruption) near the cervix.  Everything I read on placental abruption says that this doesn't usually happen before 20-weeks and yet apparently, this is what I have.  The doctor said to take it easy and that 90% of cases resolve themselves as the uterus grows and the placenta is pulled up away from the cervix and the tear heals.  I am more than a little stressed, because there is also a risk of miscarriage associated with the abruption.  I'd like for once to not have to worry about this pregnancy. . .