Had my first ultrasound yesterday

Raven01

DH and I went for a dating ultrasound yesterday, and we were able to see our little bean! It measured at 5w3d, and has a heartbeat of 105 bpm. The receptionist at my OB's office mentioned when I called today that the measurement may have been slightly off and I may be a little further along. She said she thinks this because 5w3d is very early to see the lil bean and to record such a strong heartbeat.

My last pregnancy did not grow properly, so I'm a very nervous FTM. I had some cramping after the ultrasound - no spotting, just cramps, and wanted to ask if this is normal?