Empty gestational sac at 6 weeks?

Hi everyone,
I've totally gone crazy from reading and googling. I've had irregular bleeding for months. Went to the gynecologist. All tests were fine. Unexplained bleeding, especially during sleep.
Jan 19: He saw a small thickening in the uterus, but said it couldn't cause the bleeding. Eventually, he told me to track ovulation. Jan 31: Tested positive for 3 days in a row! Pregnancy test on Feb 6 was positive! 2-3 weeks! How strange, despite the heavy bleeding.
Went to the gynecologist on Feb 6. Ultrasound 1: gestational sac 3 mm, which could make sense for such an early pregnancy.
Feb 9: Ultrasound 2: 5 mm, same thing.
Feb 16: Ultrasound 3: 8 mm with a yolk sac! According to my calculations, I should be 6 weeks and 4 days. Based on intercourse on Jan 15 (no regular cycle). The sonographer said: definitely too small for 6 weeks and 4 days, but luckily the gestational sac is growing. We'll have to wait and see, it could go either way.
Monday, Feb 20: New ultrasound in Z-H, so 4 days after the last one. Very exciting. I've had some bleeding/discharge while wiping, but that's been going on since the beginning (and before).
With my second child, I had the first ultrasound at 8 weeks: empty gestational sac/had the bad news talk. Went on vacation with packs of pads, waiting for miscarriage. About 2 weeks later, had an ultrasound abroad to check if it was gone. The answer was: yes, madam, the hands and feet are moving! So that's my miracle that was hiding somewhere. Unexplainable.
But now? So exciting that I'm going crazy. Hopefully, the ultrasound was too early and Monday will bring better news.