I don't know how I feel...

Had my 8 week ultrasound today. The last one was two weeks ago and saw a baby and tiny heartbeat. Today the tech was really quiet then left the room to "check measurements" she then came back and said she couldn't see anything in the sac. She said sometimes they hide but she didn't seem hopeful. Then all they told me was my OB will call me tomorrow. I don't know how to feel.., I feel like it will be bad news that I'm having my third miscarriage in a row... I just want a healthy baby.. :'(