A little worried but trying to stay positive.

Just got done with our first ultrasound... They found the baby right away with an abdominal ultrasound but we had to switch to a vaginal ultrasound. I am supposed to be 7w6d... But we are measuring 6w2d... And our little peanuts heartbeat is slow... Doctor said it seems normal for the size I am measuring at, but not were in am supposed to be. They are still treating me as a Threatened Miscarriage.... My husband says stay positive. I go back in 2 weeks for a other ultrasound. Has anyone else been through this and been ok? Positive stories or thoughts will really help!