Ahhh I understand lah, it's scary when the sonographer tu macam tak excited nak let you hear the heartbeat kan. 8 weeks pun heartbeat mmg sometimes susah nak dengar clearly on Doppler, so jangan worry dulu! Please go for that repeat scan as advised , doctor knows best, and at least you'll get proper answers then instead of guessing. Praying everything's good for you, mama!