Developed yolk sac??

So last week I went in for my first ultrasound. According to my last period I should have been 8 weeks. They found an empty gestational sac measuring at 6 weeks. I was convinced it was a blighted ovum. Today I went in again and this time there was a yolk sac. I had blood work done Thursday and Saturday and my numbers didn’t double so has me worried. I’m also bleeding but not a lot and it’s dark brown almost black.

Has anyone had this happen to them and go on to have a successful pregnancy?? Looking to hear any similar experiences good and bad