FREAKING OUT!

My blood type is rh (-) and my husband's is rh (+). I was able to have a healthy pregnancy with my first son who is now two years old. I had the rhogam shot with him and everything was fine. I was reading that typically the first baby is fine but now I'm pregnant again and just had my first prenatal exam (no ultrasound yet) and it slipped my mind to talk to the doctor about it. I'm worried my body may be sensitized to this new baby growing in me. I'm scared I could possibly lose the baby, I'm 8 weeks.