Pregnancy Timeline Confusion

Hi everyone. I'm really confused. My lmp was on the 26th dec 2019. And I was tested positive pregnant on the 1st feb 2020. The thing is, since the day we did first scan, we can only see the sac. Until somewhere around week 7-8, the gynae claimed that he couldn't see embryo. So we went to another gynae, and he "confirmed" that i had blighted ovum and i was on my 9th week. So we went to KKH with the thought of doing D&C, lo and behold! The doc told us (from the ultrasound scan) we have a 5 week baby! Tho there's no heartbeat yet hence we have to come back in 2 weeks time. I'm so lost and confused with the timeline like the edd, or is my baby really at 5 weeks...