Missed miscarriage

Today I went in for my 8 week US and was told there is no HB and baby was measuring at 6 weeks 5 days...I had a previous US at 6weeks 1 day at HB was at 145...I went for blood work at 7 weeks 1 day and hcg and progesterone were all in normal range for my pregnancy dating. The ultrasound was quick today, is it possible the tech missed the HB or the baby was positioned where the HB couldn't be seen? The doc told me to take cytotec to start contractions. I'm hesitating beginning that treatment. Should I get a 2nd opinion? Has anyone had a misdiagnosed miscarriage? 😭💔