I have a similar story but I was 7.5 weeks so it is pretty certain this is a bad outcome for me. You are undergoing the correct treatments to see if things are on track or not.
I am still having pregnancy symptoms and no bleeding but I understand it can take a while for the hormone levels to drop.
Take care of yourself while you are waiting to find out and sorry you are going through this.
I agree with adgal. Your right on the border of when the heartbeat shows up. Hopefully, you'll see it on your next ultrasound.
Its hard to say. Does 6 weeks match your dates? A heartbeat is typically detected anywhere from 5 1/2 to 6 1/2 weeks so it could be too early. I can't comment on the abnormally shaped sac as I haven't had that experience myself. I wish you well.