I was told my pregnancy may not be healthy??

So, today I should be 10 weeks. I went for my first ultrasound today my ob said the ultrasound machine was fuzzy and old but preceded on with the US . Found out that the baby is only the size of a piece of rice, with a big yolk sack, AND saw another sack next to it, my ob saw no flutter of a heart beat and said I look 5 weeks. She then said it doesnt look like a healthy pregnancy and gave me three options just in case of the worst for a misscarage. So she had me go to another hospital for a better ultrasound and a second opinion today as well by another doctor. She called me back and she told me he didnt see anything wrong that would make me have a misscarage, he thought he saw a slight flutter of something, and said he saw nothing of two egg sacks just the one. She then went to tell me I needed bloond drawn for my hcg levels. Got that done today and another this saturday, but she still preceded to say she thinks it's not a healthy pregnancy. Who do I believe?! :(