I lost my shrimp today...

Me and my husband have been trying for almost a year. We went u see fertility treatments and IUI. We finally gor pregnant at the end of May. My RE was skeptical because my HCG levels were low but finally at 6 weeks we were in the clear. I still had weekly ultrasounds to make sure. Well today my little shrimp at 8 weeks (That's what my son Ethan calls him.) has stop growing and no longer has a heartbeat. My RE will perform a D&C on Friday. I can't stop crying and I just don't understand. My heart aches so much...