Heart beat, c section and hand Doppler.

I’m still rather early in my pregnancy, and my last appointment I was 13 weeks. My doctor had a hard time finding baby’s heart beat with a hand Doppler. She did mention that the c section scar can make it difficult, I’ve had 2 c sections ....(I’m also overweight) For other ladies that have c section scars when was the doctor able to pick up baby’s heart beat with the Doppler?