High and increasing hcg but only a sac?!

So I had a chemical pregnancy and got pregnant again right after no period in between but confirmed hcg levels went back to zero, so definitely a new pregnancy. The initial levels seemed fine and went in for a vaginal ultrasound at what they thought would be 6 weeks possibly and only the gestational sac was found and my levels were around 43,000. Doc said seemed high so had me come back 2days later to check levels again and do another ultrasound, same thing just a sac. My levels increased to over 70,000 so she’s having me come back Tuesday. We don’t know how far I am so could be early but being monitored for blighted ovium or molar pregnancy. Any success stories with similar hcg levels and ultrasound?